Practical way to manage skill unlearn.

L2J_Mobius_01.0_Ertheia/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -271,7 +270,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -665,7 +664,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeAutoGet, true, player);
 	}
@@ -680,9 +679,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -733,6 +732,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -749,7 +777,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeAutoGet, includeRequiredItems, holder);
@@ -1460,14 +1488,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1477,10 +1506,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1498,6 +1529,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_01.0_Ertheia/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_01.0_Ertheia/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 import java.util.Objects;
 import java.util.stream.Collectors;
 
@@ -34,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -71,7 +71,7 @@ public class AcquireSkillList implements IClientOutgoingPacket
 				packet.writeQ(item.getCount());
 			}
 			
-			final List<Skill> skillRem = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			final Collection<Skill> skillRem = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
 			packet.writeC(skillRem.size());
 			for (Skill skillRemove : skillRem)
 			{

L2J_Mobius_01.0_Ertheia/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;

L2J_Mobius_02.5_Underground/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -271,7 +270,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -665,7 +664,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeAutoGet, true, player);
 	}
@@ -680,9 +679,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -733,6 +732,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -749,7 +777,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeAutoGet, includeRequiredItems, holder);
@@ -1460,14 +1488,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1477,10 +1506,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1498,6 +1529,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_02.5_Underground/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_02.5_Underground/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 import java.util.Objects;
 import java.util.stream.Collectors;
 
@@ -34,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -71,12 +71,12 @@ public class AcquireSkillList implements IClientOutgoingPacket
 				packet.writeQ(item.getCount());
 			}
 			
-			final List<Skill> skillRem = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
-			packet.writeC(skillRem.size());
+			packet.writeC(removeSkills.size());
-			for (Skill skillRemove : skillRem)
+			for (Skill removed : removeSkills)
 			{
-				packet.writeD(skillRemove.getId());
+				packet.writeD(removed.getId());
-				packet.writeD(skillRemove.getLevel());
+				packet.writeD(removed.getLevel());
 			}
 		}
 		return true;

L2J_Mobius_02.5_Underground/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;

L2J_Mobius_03.0_Helios/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -271,7 +270,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -665,7 +664,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeAutoGet, true, player);
 	}
@@ -680,9 +679,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -733,6 +732,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -749,7 +777,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeAutoGet, includeRequiredItems, holder);
@@ -1460,14 +1488,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1477,10 +1506,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1498,6 +1529,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_03.0_Helios/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_03.0_Helios/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 import java.util.Objects;
 import java.util.stream.Collectors;
 
@@ -34,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -71,12 +71,12 @@ public class AcquireSkillList implements IClientOutgoingPacket
 				packet.writeQ(item.getCount());
 			}
 			
-			final List<Skill> skillRem = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
-			packet.writeC(skillRem.size());
+			packet.writeC(removeSkills.size());
-			for (Skill skillRemove : skillRem)
+			for (Skill removed : removeSkills)
 			{
-				packet.writeD(skillRemove.getId());
+				packet.writeD(removed.getId());
-				packet.writeD(skillRemove.getLevel());
+				packet.writeD(removed.getLevel());
 			}
 		}
 		return true;

L2J_Mobius_03.0_Helios/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;

L2J_Mobius_04.0_GrandCrusade/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -271,7 +270,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -665,7 +664,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeAutoGet, true, player);
 	}
@@ -680,9 +679,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -733,6 +732,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -749,7 +777,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeAutoGet, includeRequiredItems, holder);
@@ -1460,14 +1488,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1477,10 +1506,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1498,6 +1529,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_04.0_GrandCrusade/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_04.0_GrandCrusade/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 import java.util.Objects;
 import java.util.stream.Collectors;
 
@@ -34,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -71,12 +71,12 @@ public class AcquireSkillList implements IClientOutgoingPacket
 				packet.writeQ(item.getCount());
 			}
 			
-			final List<Skill> skillRem = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
-			packet.writeC(skillRem.size());
+			packet.writeC(removeSkills.size());
-			for (Skill skillRemove : skillRem)
+			for (Skill removed : removeSkills)
 			{
-				packet.writeD(skillRemove.getId());
+				packet.writeD(removed.getId());
-				packet.writeD(skillRemove.getLevel());
+				packet.writeD(removed.getLevel());
 			}
 		}
 		return true;

L2J_Mobius_04.0_GrandCrusade/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;

L2J_Mobius_05.0_Salvation/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -271,7 +270,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -665,7 +664,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeAutoGet, true, player);
 	}
@@ -680,9 +679,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -733,6 +732,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -749,7 +777,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeAutoGet, includeRequiredItems, holder);
@@ -1460,14 +1488,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1477,10 +1506,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1498,6 +1529,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_05.0_Salvation/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_05.0_Salvation/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 import java.util.Objects;
 import java.util.stream.Collectors;
 
@@ -34,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -65,18 +65,20 @@ public class AcquireSkillList implements IClientOutgoingPacket
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(skill.getDualClassLevel());
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0x00 : 0x01);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
-			final List<Skill> skillRem = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			
-			packet.writeC(skillRem.size());
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
-			for (Skill skillRemove : skillRem)
+			packet.writeC(removeSkills.size());
+			for (Skill removed : removeSkills)
 			{
-				packet.writeD(skillRemove.getId());
+				packet.writeD(removed.getId());
-				packet.writeD(skillRemove.getLevel());
+				packet.writeD(removed.getLevel());
 			}
 		}
 		return true;

L2J_Mobius_05.0_Salvation/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;

L2J_Mobius_05.5_EtinasFate/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -271,7 +270,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -665,7 +664,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeAutoGet, true, player);
 	}
@@ -680,9 +679,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -733,6 +732,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -749,7 +777,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeAutoGet, includeRequiredItems, holder);
@@ -1460,14 +1488,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1477,10 +1506,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1498,6 +1529,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_05.5_EtinasFate/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_05.5_EtinasFate/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 import java.util.Objects;
 import java.util.stream.Collectors;
 
@@ -34,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -65,18 +65,20 @@ public class AcquireSkillList implements IClientOutgoingPacket
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(skill.getDualClassLevel());
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0x00 : 0x01);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
-			final List<Skill> skillRem = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			
-			packet.writeC(skillRem.size());
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
-			for (Skill skillRemove : skillRem)
+			packet.writeC(removeSkills.size());
+			for (Skill removed : removeSkills)
 			{
-				packet.writeD(skillRemove.getId());
+				packet.writeD(removed.getId());
-				packet.writeD(skillRemove.getLevel());
+				packet.writeD(removed.getLevel());
 			}
 		}
 		return true;

L2J_Mobius_05.5_EtinasFate/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;

L2J_Mobius_06.0_Fafurion/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -271,7 +270,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -666,7 +665,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeByFp, includeAutoGet, true, player);
 	}
@@ -682,9 +681,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -735,6 +734,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -752,7 +780,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeByFp, includeAutoGet, includeRequiredItems, holder);
@@ -1463,14 +1491,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1480,10 +1509,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()) || (!includeByFp && (skill.getSkillId() > 11399) && (skill.getSkillId() < 11405)))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1501,6 +1532,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_06.0_Fafurion/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, No LearnedByFP, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_06.0_Fafurion/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 import java.util.Objects;
 import java.util.stream.Collectors;
 
@@ -34,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -65,18 +65,20 @@ public class AcquireSkillList implements IClientOutgoingPacket
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(skill.getDualClassLevel());
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0x00 : 0x01);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
-			final List<Skill> skillRem = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			
-			packet.writeC(skillRem.size());
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
-			for (Skill skillRemove : skillRem)
+			packet.writeC(removeSkills.size());
+			for (Skill removed : removeSkills)
 			{
-				packet.writeD(skillRemove.getId());
+				packet.writeD(removed.getId());
-				packet.writeD(skillRemove.getLevel());
+				packet.writeD(removed.getLevel());
 			}
 		}
 		return true;

L2J_Mobius_06.0_Fafurion/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;

L2J_Mobius_07.0_PreludeOfWar/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -271,7 +270,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -666,7 +665,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeByFp, includeAutoGet, true, player);
 	}
@@ -682,9 +681,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -735,6 +734,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -752,7 +780,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeByFp, includeAutoGet, includeRequiredItems, holder);
@@ -1463,14 +1491,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1480,10 +1509,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()) || (!includeByFp && (skill.getSkillId() > 11399) && (skill.getSkillId() < 11405)))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1501,6 +1532,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_07.0_PreludeOfWar/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, No LearnedByFP, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_07.0_PreludeOfWar/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 import java.util.Objects;
 import java.util.stream.Collectors;
 
@@ -34,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -65,18 +65,20 @@ public class AcquireSkillList implements IClientOutgoingPacket
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(skill.getDualClassLevel());
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0x00 : 0x01);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
-			final List<Skill> skillRem = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			
-			packet.writeC(skillRem.size());
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
-			for (Skill skillRemove : skillRem)
+			packet.writeC(removeSkills.size());
+			for (Skill removed : removeSkills)
 			{
-				packet.writeD(skillRemove.getId());
+				packet.writeD(removed.getId());
-				packet.writeD(skillRemove.getLevel());
+				packet.writeD(removed.getLevel());
 			}
 		}
 		return true;

L2J_Mobius_07.0_PreludeOfWar/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;

L2J_Mobius_08.2_Homunculus/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -271,7 +270,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -666,7 +665,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeByFp, includeAutoGet, true, player);
 	}
@@ -682,9 +681,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -735,6 +734,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -752,7 +780,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeByFp, includeAutoGet, includeRequiredItems, holder);
@@ -1463,14 +1491,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1480,10 +1509,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()) || (!includeByFp && (skill.getSkillId() > 11399) && (skill.getSkillId() < 11405)))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1501,6 +1532,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_08.2_Homunculus/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, No LearnedByFP, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_08.2_Homunculus/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 import java.util.Objects;
 import java.util.stream.Collectors;
 
@@ -34,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -65,18 +65,20 @@ public class AcquireSkillList implements IClientOutgoingPacket
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(skill.getDualClassLevel());
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0x00 : 0x01);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
-			final List<Skill> skillRem = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			
-			packet.writeC(skillRem.size());
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
-			for (Skill skillRemove : skillRem)
+			packet.writeC(removeSkills.size());
+			for (Skill removed : removeSkills)
 			{
-				packet.writeD(skillRemove.getId());
+				packet.writeD(removed.getId());
-				packet.writeD(skillRemove.getLevel());
+				packet.writeD(removed.getLevel());
 			}
 		}
 		return true;

L2J_Mobius_08.2_Homunculus/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;

L2J_Mobius_09.2_ReturnOfTheQueenAnt/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -271,7 +270,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -666,7 +665,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeByFp, includeAutoGet, true, player);
 	}
@@ -682,9 +681,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -735,6 +734,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -752,7 +780,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeByFp, includeAutoGet, includeRequiredItems, holder);
@@ -1463,14 +1491,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1480,10 +1509,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()) || (!includeByFp && (skill.getSkillId() > 11399) && (skill.getSkillId() < 11405)))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1501,6 +1532,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_09.2_ReturnOfTheQueenAnt/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, No LearnedByFP, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_09.2_ReturnOfTheQueenAnt/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 import java.util.Objects;
 import java.util.stream.Collectors;
 
@@ -34,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -65,18 +65,20 @@ public class AcquireSkillList implements IClientOutgoingPacket
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(skill.getDualClassLevel());
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0x00 : 0x01);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
-			final List<Skill> skillRem = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			
-			packet.writeC(skillRem.size());
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
-			for (Skill skillRemove : skillRem)
+			packet.writeC(removeSkills.size());
+			for (Skill removed : removeSkills)
 			{
-				packet.writeD(skillRemove.getId());
+				packet.writeD(removed.getId());
-				packet.writeD(skillRemove.getLevel());
+				packet.writeD(removed.getLevel());
 			}
 		}
 		return true;

L2J_Mobius_09.2_ReturnOfTheQueenAnt/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;

L2J_Mobius_10.0_MasterClass/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -271,7 +270,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -666,7 +665,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeByFp, includeAutoGet, true, player);
 	}
@@ -682,9 +681,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -735,6 +734,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -752,7 +780,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeByFp, includeAutoGet, includeRequiredItems, holder);
@@ -1463,14 +1491,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeByFp, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1480,10 +1509,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()) || (!includeByFp && (skill.getSkillId() > 11399) && (skill.getSkillId() < 11405)))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1501,6 +1532,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_10.0_MasterClass/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, No LearnedByFP, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_10.0_MasterClass/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 import java.util.Objects;
 import java.util.stream.Collectors;
 
@@ -34,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -65,18 +65,20 @@ public class AcquireSkillList implements IClientOutgoingPacket
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(skill.getDualClassLevel());
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0x00 : 0x01);
+			
 			packet.writeC(skill.getRequiredItems().size());
 			for (ItemHolder item : skill.getRequiredItems())
 			{
 				packet.writeD(item.getId());
 				packet.writeQ(item.getCount());
 			}
-			final List<Skill> skillRem = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			
-			packet.writeC(skillRem.size());
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
-			for (Skill skillRemove : skillRem)
+			packet.writeC(removeSkills.size());
+			for (Skill removed : removeSkills)
 			{
-				packet.writeD(skillRemove.getId());
+				packet.writeD(removed.getId());
-				packet.writeD(skillRemove.getLevel());
+				packet.writeD(removed.getLevel());
 			}
 		}
 		return true;

L2J_Mobius_10.0_MasterClass/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;

L2J_Mobius_Classic_2.0_Saviors/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -39,7 +38,6 @@ import org.w3c.dom.Node;
 import org.l2jmobius.Config;
 import org.l2jmobius.commons.util.IXmlReader;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
-import org.l2jmobius.gameserver.enums.CategoryType;
 import org.l2jmobius.gameserver.enums.ClassId;
 import org.l2jmobius.gameserver.enums.Race;
 import org.l2jmobius.gameserver.enums.SocialClass;
@@ -271,7 +269,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -665,7 +663,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeAutoGet, true, player);
 	}
@@ -680,9 +678,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -691,7 +689,6 @@ public class SkillTreeData implements IXmlReader
 			return result;
 		}
 		
-		final boolean isAwaken = player.isInCategory(CategoryType.SIXTH_CLASS_GROUP) && ((player.getRace() != Race.ERTHEIA) || player.isDualClassActive());
 		for (Entry<Long, SkillLearn> entry : skills.entrySet())
 		{
 			final SkillLearn skill = entry.getValue();
@@ -706,11 +703,6 @@ public class SkillTreeData implements IXmlReader
 				continue;
 			}
 			
-			if (isAwaken && !isCurrentClassSkillNoParent(classId, entry.getKey()) && !isAwakenSaveSkill(player.getClassId(), skill.getSkillId()))
-			{
-				continue;
-			}
-			
 			if (player.getLevel() >= skill.getGetLevel())
 			{
 				if (skill.getSkillLevel() > SkillData.getInstance().getMaxLevel(skill.getSkillId()))
@@ -733,6 +725,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -749,7 +770,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeAutoGet, includeRequiredItems, holder);
@@ -825,20 +846,6 @@ public class SkillTreeData implements IXmlReader
 		}
 		
 		final Race race = player.getRace();
-		final boolean isAwaken = player.isInCategory(CategoryType.SIXTH_CLASS_GROUP);
-		
-		// Race skills
-		if (isAwaken)
-		{
-			for (SkillLearn skill : getRaceSkillTree(race))
-			{
-				if (player.getKnownSkill(skill.getSkillId()) == null)
-				{
-					result.add(skill);
-				}
-			}
-		}
-		
 		for (SkillLearn skill : skills.values())
 		{
 			if (!skill.getRaces().isEmpty() && !skill.getRaces().contains(race))
@@ -846,8 +853,6 @@ public class SkillTreeData implements IXmlReader
 				continue;
 			}
 			
-			final int maxLevel = SkillData.getInstance().getMaxLevel(skill.getSkillId());
-			final long hashCode = SkillData.getSkillHashCode(skill.getSkillId(), maxLevel);
 			if (skill.isAutoGet() && (player.getLevel() >= skill.getGetLevel()))
 			{
 				final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -858,7 +863,7 @@ public class SkillTreeData implements IXmlReader
 						result.add(skill);
 					}
 				}
-				else if (!isAwaken || isCurrentClassSkillNoParent(player.getClassId(), hashCode) || isAwakenSaveSkill(player.getClassId(), skill.getSkillId()))
+				else
 				{
 					result.add(skill);
 				}
@@ -1448,14 +1453,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1465,10 +1471,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1486,6 +1494,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_Classic_2.0_Saviors/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_Classic_2.0_Saviors/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,13 +16,16 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
+import java.util.Objects;
+import java.util.stream.Collectors;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.data.xml.SkillTreeData;
 import org.l2jmobius.gameserver.model.SkillLearn;
 import org.l2jmobius.gameserver.model.actor.instance.PlayerInstance;
 import org.l2jmobius.gameserver.model.holders.ItemHolder;
+import org.l2jmobius.gameserver.model.skills.Skill;
 import org.l2jmobius.gameserver.network.OutgoingPackets;
 
 /**
@@ -31,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -56,30 +59,26 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		packet.writeH(_learnable.size());
 		for (SkillLearn skill : _learnable)
 		{
-			if (skill == null)
-			{
-				continue;
-			}
-			
 			packet.writeD(skill.getSkillId());
 			packet.writeH(skill.getSkillLevel());
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0x00); // Skill dual class level.
-			if (!skill.getRequiredItems().isEmpty())
+			
+			packet.writeC(skill.getRequiredItems().size());
+			for (ItemHolder item : skill.getRequiredItems())
 			{
-				for (ItemHolder item : skill.getRequiredItems())
+				packet.writeD(item.getId());
-				{
+				packet.writeQ(item.getCount());
-					packet.writeC(0x01);
-					packet.writeD(item.getId());
-					packet.writeQ(item.getCount());
-				}
 			}
-			else
+			
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			packet.writeC(removeSkills.size());
+			for (Skill removed : removeSkills)
 			{
-				packet.writeC(0x00);
+				packet.writeD(removed.getId());
+				packet.writeD(removed.getLevel());
 			}
-			packet.writeC(0x00);
 		}
 		return true;
 	}

L2J_Mobius_Classic_2.0_Saviors/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;

L2J_Mobius_Classic_2.1_Zaken/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -39,7 +38,6 @@ import org.w3c.dom.Node;
 import org.l2jmobius.Config;
 import org.l2jmobius.commons.util.IXmlReader;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
-import org.l2jmobius.gameserver.enums.CategoryType;
 import org.l2jmobius.gameserver.enums.ClassId;
 import org.l2jmobius.gameserver.enums.Race;
 import org.l2jmobius.gameserver.enums.SocialClass;
@@ -271,7 +269,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -665,7 +663,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeAutoGet, true, player);
 	}
@@ -680,9 +678,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -691,7 +689,6 @@ public class SkillTreeData implements IXmlReader
 			return result;
 		}
 		
-		final boolean isAwaken = player.isInCategory(CategoryType.SIXTH_CLASS_GROUP) && ((player.getRace() != Race.ERTHEIA) || player.isDualClassActive());
 		for (Entry<Long, SkillLearn> entry : skills.entrySet())
 		{
 			final SkillLearn skill = entry.getValue();
@@ -706,11 +703,6 @@ public class SkillTreeData implements IXmlReader
 				continue;
 			}
 			
-			if (isAwaken && !isCurrentClassSkillNoParent(classId, entry.getKey()) && !isAwakenSaveSkill(player.getClassId(), skill.getSkillId()))
-			{
-				continue;
-			}
-			
 			if (player.getLevel() >= skill.getGetLevel())
 			{
 				if (skill.getSkillLevel() > SkillData.getInstance().getMaxLevel(skill.getSkillId()))
@@ -733,6 +725,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -749,7 +770,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeAutoGet, includeRequiredItems, holder);
@@ -825,20 +846,6 @@ public class SkillTreeData implements IXmlReader
 		}
 		
 		final Race race = player.getRace();
-		final boolean isAwaken = player.isInCategory(CategoryType.SIXTH_CLASS_GROUP);
-		
-		// Race skills
-		if (isAwaken)
-		{
-			for (SkillLearn skill : getRaceSkillTree(race))
-			{
-				if (player.getKnownSkill(skill.getSkillId()) == null)
-				{
-					result.add(skill);
-				}
-			}
-		}
-		
 		for (SkillLearn skill : skills.values())
 		{
 			if (!skill.getRaces().isEmpty() && !skill.getRaces().contains(race))
@@ -846,8 +853,6 @@ public class SkillTreeData implements IXmlReader
 				continue;
 			}
 			
-			final int maxLevel = SkillData.getInstance().getMaxLevel(skill.getSkillId());
-			final long hashCode = SkillData.getSkillHashCode(skill.getSkillId(), maxLevel);
 			if (skill.isAutoGet() && (player.getLevel() >= skill.getGetLevel()))
 			{
 				final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -858,7 +863,7 @@ public class SkillTreeData implements IXmlReader
 						result.add(skill);
 					}
 				}
-				else if (!isAwaken || isCurrentClassSkillNoParent(player.getClassId(), hashCode) || isAwakenSaveSkill(player.getClassId(), skill.getSkillId()))
+				else
 				{
 					result.add(skill);
 				}
@@ -1448,14 +1453,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1465,10 +1471,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1486,6 +1494,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_Classic_2.1_Zaken/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_Classic_2.1_Zaken/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,13 +16,16 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
+import java.util.Objects;
+import java.util.stream.Collectors;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.data.xml.SkillTreeData;
 import org.l2jmobius.gameserver.model.SkillLearn;
 import org.l2jmobius.gameserver.model.actor.instance.PlayerInstance;
 import org.l2jmobius.gameserver.model.holders.ItemHolder;
+import org.l2jmobius.gameserver.model.skills.Skill;
 import org.l2jmobius.gameserver.network.OutgoingPackets;
 
 /**
@@ -31,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -56,30 +59,26 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		packet.writeH(_learnable.size());
 		for (SkillLearn skill : _learnable)
 		{
-			if (skill == null)
-			{
-				continue;
-			}
-			
 			packet.writeD(skill.getSkillId());
 			packet.writeH(skill.getSkillLevel());
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0x00); // Skill dual class level.
-			if (!skill.getRequiredItems().isEmpty())
+			
+			packet.writeC(skill.getRequiredItems().size());
+			for (ItemHolder item : skill.getRequiredItems())
 			{
-				for (ItemHolder item : skill.getRequiredItems())
+				packet.writeD(item.getId());
-				{
+				packet.writeQ(item.getCount());
-					packet.writeC(0x01);
-					packet.writeD(item.getId());
-					packet.writeQ(item.getCount());
-				}
 			}
-			else
+			
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			packet.writeC(removeSkills.size());
+			for (Skill removed : removeSkills)
 			{
-				packet.writeC(0x00);
+				packet.writeD(removed.getId());
+				packet.writeD(removed.getLevel());
 			}
-			packet.writeC(0x00);
 		}
 		return true;
 	}

L2J_Mobius_Classic_2.1_Zaken/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;

L2J_Mobius_Classic_2.2_Antharas/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -39,7 +38,6 @@ import org.w3c.dom.Node;
 import org.l2jmobius.Config;
 import org.l2jmobius.commons.util.IXmlReader;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
-import org.l2jmobius.gameserver.enums.CategoryType;
 import org.l2jmobius.gameserver.enums.ClassId;
 import org.l2jmobius.gameserver.enums.Race;
 import org.l2jmobius.gameserver.enums.SocialClass;
@@ -271,7 +269,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -665,7 +663,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeAutoGet, true, player);
 	}
@@ -680,9 +678,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -691,7 +689,6 @@ public class SkillTreeData implements IXmlReader
 			return result;
 		}
 		
-		final boolean isAwaken = player.isInCategory(CategoryType.SIXTH_CLASS_GROUP) && ((player.getRace() != Race.ERTHEIA) || player.isDualClassActive());
 		for (Entry<Long, SkillLearn> entry : skills.entrySet())
 		{
 			final SkillLearn skill = entry.getValue();
@@ -706,11 +703,6 @@ public class SkillTreeData implements IXmlReader
 				continue;
 			}
 			
-			if (isAwaken && !isCurrentClassSkillNoParent(classId, entry.getKey()) && !isAwakenSaveSkill(player.getClassId(), skill.getSkillId()))
-			{
-				continue;
-			}
-			
 			if (player.getLevel() >= skill.getGetLevel())
 			{
 				if (skill.getSkillLevel() > SkillData.getInstance().getMaxLevel(skill.getSkillId()))
@@ -733,6 +725,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -749,7 +770,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeAutoGet, includeRequiredItems, holder);
@@ -825,20 +846,6 @@ public class SkillTreeData implements IXmlReader
 		}
 		
 		final Race race = player.getRace();
-		final boolean isAwaken = player.isInCategory(CategoryType.SIXTH_CLASS_GROUP);
-		
-		// Race skills
-		if (isAwaken)
-		{
-			for (SkillLearn skill : getRaceSkillTree(race))
-			{
-				if (player.getKnownSkill(skill.getSkillId()) == null)
-				{
-					result.add(skill);
-				}
-			}
-		}
-		
 		for (SkillLearn skill : skills.values())
 		{
 			if (!skill.getRaces().isEmpty() && !skill.getRaces().contains(race))
@@ -846,8 +853,6 @@ public class SkillTreeData implements IXmlReader
 				continue;
 			}
 			
-			final int maxLevel = SkillData.getInstance().getMaxLevel(skill.getSkillId());
-			final long hashCode = SkillData.getSkillHashCode(skill.getSkillId(), maxLevel);
 			if (skill.isAutoGet() && (player.getLevel() >= skill.getGetLevel()))
 			{
 				final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -858,7 +863,7 @@ public class SkillTreeData implements IXmlReader
 						result.add(skill);
 					}
 				}
-				else if (!isAwaken || isCurrentClassSkillNoParent(player.getClassId(), hashCode) || isAwakenSaveSkill(player.getClassId(), skill.getSkillId()))
+				else
 				{
 					result.add(skill);
 				}
@@ -1448,14 +1453,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1465,10 +1471,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1486,6 +1494,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_Classic_2.2_Antharas/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_Classic_2.2_Antharas/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,13 +16,16 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
+import java.util.Objects;
+import java.util.stream.Collectors;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.data.xml.SkillTreeData;
 import org.l2jmobius.gameserver.model.SkillLearn;
 import org.l2jmobius.gameserver.model.actor.instance.PlayerInstance;
 import org.l2jmobius.gameserver.model.holders.ItemHolder;
+import org.l2jmobius.gameserver.model.skills.Skill;
 import org.l2jmobius.gameserver.network.OutgoingPackets;
 
 /**
@@ -31,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -56,31 +59,27 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		packet.writeH(_learnable.size());
 		for (SkillLearn skill : _learnable)
 		{
-			if (skill == null)
-			{
-				continue;
-			}
-			
 			packet.writeD(skill.getSkillId());
 			packet.writeH(skill.getSkillLevel());
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0x00); // Skill dual class level.
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0x00 : 0x01);
-			if (!skill.getRequiredItems().isEmpty())
+			
+			packet.writeC(skill.getRequiredItems().size());
+			for (ItemHolder item : skill.getRequiredItems())
 			{
-				for (ItemHolder item : skill.getRequiredItems())
+				packet.writeD(item.getId());
-				{
+				packet.writeQ(item.getCount());
-					packet.writeC(0x01);
-					packet.writeD(item.getId());
-					packet.writeQ(item.getCount());
-				}
 			}
-			else
+			
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			packet.writeC(removeSkills.size());
+			for (Skill removed : removeSkills)
 			{
-				packet.writeC(0x00);
+				packet.writeD(removed.getId());
+				packet.writeD(removed.getLevel());
 			}
-			packet.writeC(0x00);
 		}
 		return true;
 	}

L2J_Mobius_Classic_2.2_Antharas/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;

L2J_Mobius_Classic_2.3_SevenSigns/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -39,7 +38,6 @@ import org.w3c.dom.Node;
 import org.l2jmobius.Config;
 import org.l2jmobius.commons.util.IXmlReader;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
-import org.l2jmobius.gameserver.enums.CategoryType;
 import org.l2jmobius.gameserver.enums.ClassId;
 import org.l2jmobius.gameserver.enums.Race;
 import org.l2jmobius.gameserver.enums.SocialClass;
@@ -271,7 +269,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -665,7 +663,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeAutoGet, true, player);
 	}
@@ -680,9 +678,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -691,7 +689,6 @@ public class SkillTreeData implements IXmlReader
 			return result;
 		}
 		
-		final boolean isAwaken = player.isInCategory(CategoryType.SIXTH_CLASS_GROUP) && ((player.getRace() != Race.ERTHEIA) || player.isDualClassActive());
 		for (Entry<Long, SkillLearn> entry : skills.entrySet())
 		{
 			final SkillLearn skill = entry.getValue();
@@ -706,11 +703,6 @@ public class SkillTreeData implements IXmlReader
 				continue;
 			}
 			
-			if (isAwaken && !isCurrentClassSkillNoParent(classId, entry.getKey()) && !isAwakenSaveSkill(player.getClassId(), skill.getSkillId()))
-			{
-				continue;
-			}
-			
 			if (player.getLevel() >= skill.getGetLevel())
 			{
 				if (skill.getSkillLevel() > SkillData.getInstance().getMaxLevel(skill.getSkillId()))
@@ -733,6 +725,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -749,7 +770,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeAutoGet, includeRequiredItems, holder);
@@ -825,20 +846,6 @@ public class SkillTreeData implements IXmlReader
 		}
 		
 		final Race race = player.getRace();
-		final boolean isAwaken = player.isInCategory(CategoryType.SIXTH_CLASS_GROUP);
-		
-		// Race skills
-		if (isAwaken)
-		{
-			for (SkillLearn skill : getRaceSkillTree(race))
-			{
-				if (player.getKnownSkill(skill.getSkillId()) == null)
-				{
-					result.add(skill);
-				}
-			}
-		}
-		
 		for (SkillLearn skill : skills.values())
 		{
 			if (!skill.getRaces().isEmpty() && !skill.getRaces().contains(race))
@@ -846,8 +853,6 @@ public class SkillTreeData implements IXmlReader
 				continue;
 			}
 			
-			final int maxLevel = SkillData.getInstance().getMaxLevel(skill.getSkillId());
-			final long hashCode = SkillData.getSkillHashCode(skill.getSkillId(), maxLevel);
 			if (skill.isAutoGet() && (player.getLevel() >= skill.getGetLevel()))
 			{
 				final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -858,7 +863,7 @@ public class SkillTreeData implements IXmlReader
 						result.add(skill);
 					}
 				}
-				else if (!isAwaken || isCurrentClassSkillNoParent(player.getClassId(), hashCode) || isAwakenSaveSkill(player.getClassId(), skill.getSkillId()))
+				else
 				{
 					result.add(skill);
 				}
@@ -1448,14 +1453,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1465,10 +1471,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1486,6 +1494,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_Classic_2.3_SevenSigns/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_Classic_2.3_SevenSigns/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,13 +16,16 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
+import java.util.Objects;
+import java.util.stream.Collectors;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.data.xml.SkillTreeData;
 import org.l2jmobius.gameserver.model.SkillLearn;
 import org.l2jmobius.gameserver.model.actor.instance.PlayerInstance;
 import org.l2jmobius.gameserver.model.holders.ItemHolder;
+import org.l2jmobius.gameserver.model.skills.Skill;
 import org.l2jmobius.gameserver.network.OutgoingPackets;
 
 /**
@@ -31,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -56,31 +59,27 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		packet.writeH(_learnable.size());
 		for (SkillLearn skill : _learnable)
 		{
-			if (skill == null)
-			{
-				continue;
-			}
-			
 			packet.writeD(skill.getSkillId());
 			packet.writeH(skill.getSkillLevel());
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0x00); // Skill dual class level.
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0x00 : 0x01);
-			if (!skill.getRequiredItems().isEmpty())
+			
+			packet.writeC(skill.getRequiredItems().size());
+			for (ItemHolder item : skill.getRequiredItems())
 			{
-				for (ItemHolder item : skill.getRequiredItems())
+				packet.writeD(item.getId());
-				{
+				packet.writeQ(item.getCount());
-					packet.writeC(0x01);
-					packet.writeD(item.getId());
-					packet.writeQ(item.getCount());
-				}
 			}
-			else
+			
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			packet.writeC(removeSkills.size());
+			for (Skill removed : removeSkills)
 			{
-				packet.writeC(0x00);
+				packet.writeD(removed.getId());
+				packet.writeD(removed.getLevel());
 			}
-			packet.writeC(0x00);
 		}
 		return true;
 	}

L2J_Mobius_Classic_2.3_SevenSigns/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;

L2J_Mobius_Classic_2.4_SecretOfEmpire/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -39,7 +38,6 @@ import org.w3c.dom.Node;
 import org.l2jmobius.Config;
 import org.l2jmobius.commons.util.IXmlReader;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
-import org.l2jmobius.gameserver.enums.CategoryType;
 import org.l2jmobius.gameserver.enums.ClassId;
 import org.l2jmobius.gameserver.enums.Race;
 import org.l2jmobius.gameserver.enums.SocialClass;
@@ -271,7 +269,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -665,7 +663,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeAutoGet, true, player);
 	}
@@ -680,9 +678,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -691,7 +689,6 @@ public class SkillTreeData implements IXmlReader
 			return result;
 		}
 		
-		final boolean isAwaken = player.isInCategory(CategoryType.SIXTH_CLASS_GROUP) && ((player.getRace() != Race.ERTHEIA) || player.isDualClassActive());
 		for (Entry<Long, SkillLearn> entry : skills.entrySet())
 		{
 			final SkillLearn skill = entry.getValue();
@@ -706,11 +703,6 @@ public class SkillTreeData implements IXmlReader
 				continue;
 			}
 			
-			if (isAwaken && !isCurrentClassSkillNoParent(classId, entry.getKey()) && !isAwakenSaveSkill(player.getClassId(), skill.getSkillId()))
-			{
-				continue;
-			}
-			
 			if (player.getLevel() >= skill.getGetLevel())
 			{
 				if (skill.getSkillLevel() > SkillData.getInstance().getMaxLevel(skill.getSkillId()))
@@ -733,6 +725,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -749,7 +770,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeAutoGet, includeRequiredItems, holder);
@@ -825,20 +846,6 @@ public class SkillTreeData implements IXmlReader
 		}
 		
 		final Race race = player.getRace();
-		final boolean isAwaken = player.isInCategory(CategoryType.SIXTH_CLASS_GROUP);
-		
-		// Race skills
-		if (isAwaken)
-		{
-			for (SkillLearn skill : getRaceSkillTree(race))
-			{
-				if (player.getKnownSkill(skill.getSkillId()) == null)
-				{
-					result.add(skill);
-				}
-			}
-		}
-		
 		for (SkillLearn skill : skills.values())
 		{
 			if (!skill.getRaces().isEmpty() && !skill.getRaces().contains(race))
@@ -846,8 +853,6 @@ public class SkillTreeData implements IXmlReader
 				continue;
 			}
 			
-			final int maxLevel = SkillData.getInstance().getMaxLevel(skill.getSkillId());
-			final long hashCode = SkillData.getSkillHashCode(skill.getSkillId(), maxLevel);
 			if (skill.isAutoGet() && (player.getLevel() >= skill.getGetLevel()))
 			{
 				final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -858,7 +863,7 @@ public class SkillTreeData implements IXmlReader
 						result.add(skill);
 					}
 				}
-				else if (!isAwaken || isCurrentClassSkillNoParent(player.getClassId(), hashCode) || isAwakenSaveSkill(player.getClassId(), skill.getSkillId()))
+				else
 				{
 					result.add(skill);
 				}
@@ -1448,14 +1453,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1465,10 +1471,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1486,6 +1494,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_Classic_2.4_SecretOfEmpire/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_Classic_2.4_SecretOfEmpire/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,13 +16,16 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
+import java.util.Objects;
+import java.util.stream.Collectors;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.data.xml.SkillTreeData;
 import org.l2jmobius.gameserver.model.SkillLearn;
 import org.l2jmobius.gameserver.model.actor.instance.PlayerInstance;
 import org.l2jmobius.gameserver.model.holders.ItemHolder;
+import org.l2jmobius.gameserver.model.skills.Skill;
 import org.l2jmobius.gameserver.network.OutgoingPackets;
 
 /**
@@ -31,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -56,31 +59,27 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		packet.writeH(_learnable.size());
 		for (SkillLearn skill : _learnable)
 		{
-			if (skill == null)
-			{
-				continue;
-			}
-			
 			packet.writeD(skill.getSkillId());
 			packet.writeH(skill.getSkillLevel());
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0x00); // Skill dual class level.
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0x00 : 0x01);
-			if (!skill.getRequiredItems().isEmpty())
+			
+			packet.writeC(skill.getRequiredItems().size());
+			for (ItemHolder item : skill.getRequiredItems())
 			{
-				for (ItemHolder item : skill.getRequiredItems())
+				packet.writeD(item.getId());
-				{
+				packet.writeQ(item.getCount());
-					packet.writeC(0x01);
-					packet.writeD(item.getId());
-					packet.writeQ(item.getCount());
-				}
 			}
-			else
+			
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			packet.writeC(removeSkills.size());
+			for (Skill removed : removeSkills)
 			{
-				packet.writeC(0x00);
+				packet.writeD(removed.getId());
+				packet.writeD(removed.getLevel());
 			}
-			packet.writeC(0x00);
 		}
 		return true;
 	}

L2J_Mobius_Classic_2.4_SecretOfEmpire/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;

L2J_Mobius_Classic_3.0_TheKamael/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -270,7 +269,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -664,7 +663,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeAutoGet, true, player);
 	}
@@ -679,9 +678,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -690,7 +689,6 @@ public class SkillTreeData implements IXmlReader
 			return result;
 		}
 		
-		// final boolean isAwaken = player.isInCategory(CategoryType.SIXTH_CLASS_GROUP) && ((player.getRace() != Race.ERTHEIA) || player.isDualClassActive());
 		for (Entry<Long, SkillLearn> entry : skills.entrySet())
 		{
 			final SkillLearn skill = entry.getValue();
@@ -705,10 +703,6 @@ public class SkillTreeData implements IXmlReader
 				continue;
 			}
 			
-			// if (isAwaken && !isCurrentClassSkillNoParent(classId, entry.getKey()) && !isAwakenSaveSkill(player.getClassId(), skill.getSkillId()))
-			// {
-			// continue;
-			// }
 			if (player.getLevel() >= skill.getGetLevel())
 			{
 				if (skill.getSkillLevel() > SkillData.getInstance().getMaxLevel(skill.getSkillId()))
@@ -731,6 +725,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -747,7 +770,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeAutoGet, includeRequiredItems, holder);
@@ -823,19 +846,6 @@ public class SkillTreeData implements IXmlReader
 		}
 		
 		final Race race = player.getRace();
-		// final boolean isAwaken = player.isInCategory(CategoryType.SIXTH_CLASS_GROUP);
-		
-		// Race skills
-		// if (isAwaken)
-		// {
-		// for (SkillLearn skill : getRaceSkillTree(race))
-		// {
-		// if (player.getKnownSkill(skill.getSkillId()) == null)
-		// {
-		// result.add(skill);
-		// }
-		// }
-		// }
 		for (SkillLearn skill : skills.values())
 		{
 			if (!skill.getRaces().isEmpty() && !skill.getRaces().contains(race))
@@ -843,8 +853,6 @@ public class SkillTreeData implements IXmlReader
 				continue;
 			}
 			
-			// final int maxLevel = SkillData.getInstance().getMaxLevel(skill.getSkillId());
-			// final long hashCode = SkillData.getSkillHashCode(skill.getSkillId(), maxLevel);
 			if (skill.isAutoGet() && (player.getLevel() >= skill.getGetLevel()))
 			{
 				final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -855,7 +863,6 @@ public class SkillTreeData implements IXmlReader
 						result.add(skill);
 					}
 				}
-				// else if (!isAwaken || isCurrentClassSkillNoParent(player.getClassId(), hashCode) || isAwakenSaveSkill(player.getClassId(), skill.getSkillId()))
 				else
 				{
 					result.add(skill);
@@ -1446,14 +1453,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1463,10 +1471,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1484,6 +1494,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_Classic_3.0_TheKamael/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_Classic_3.0_TheKamael/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,13 +16,16 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
+import java.util.Objects;
+import java.util.stream.Collectors;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.data.xml.SkillTreeData;
 import org.l2jmobius.gameserver.model.SkillLearn;
 import org.l2jmobius.gameserver.model.actor.instance.PlayerInstance;
 import org.l2jmobius.gameserver.model.holders.ItemHolder;
+import org.l2jmobius.gameserver.model.skills.Skill;
 import org.l2jmobius.gameserver.network.OutgoingPackets;
 
 /**
@@ -31,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -56,31 +59,27 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		packet.writeH(_learnable.size());
 		for (SkillLearn skill : _learnable)
 		{
-			if (skill == null)
-			{
-				continue;
-			}
-			
 			packet.writeD(skill.getSkillId());
 			packet.writeH(skill.getSkillLevel());
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0x00); // Skill dual class level.
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0x00 : 0x01);
-			if (!skill.getRequiredItems().isEmpty())
+			
+			packet.writeC(skill.getRequiredItems().size());
+			for (ItemHolder item : skill.getRequiredItems())
 			{
-				for (ItemHolder item : skill.getRequiredItems())
+				packet.writeD(item.getId());
-				{
+				packet.writeQ(item.getCount());
-					packet.writeC(0x01);
-					packet.writeD(item.getId());
-					packet.writeQ(item.getCount());
-				}
 			}
-			else
+			
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			packet.writeC(removeSkills.size());
+			for (Skill removed : removeSkills)
 			{
-				packet.writeC(0x00);
+				packet.writeD(removed.getId());
+				packet.writeD(removed.getLevel());
 			}
-			packet.writeC(0x00);
 		}
 		return true;
 	}

L2J_Mobius_Classic_3.0_TheKamael/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;

L2J_Mobius_Classic_Interlude/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -39,7 +38,6 @@ import org.w3c.dom.Node;
 import org.l2jmobius.Config;
 import org.l2jmobius.commons.util.IXmlReader;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
-import org.l2jmobius.gameserver.enums.CategoryType;
 import org.l2jmobius.gameserver.enums.ClassId;
 import org.l2jmobius.gameserver.enums.Race;
 import org.l2jmobius.gameserver.enums.SocialClass;
@@ -271,7 +269,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -665,7 +663,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeAutoGet, true, player);
 	}
@@ -680,9 +678,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -691,7 +689,6 @@ public class SkillTreeData implements IXmlReader
 			return result;
 		}
 		
-		final boolean isAwaken = player.isInCategory(CategoryType.SIXTH_CLASS_GROUP) && ((player.getRace() != Race.ERTHEIA) || player.isDualClassActive());
 		for (Entry<Long, SkillLearn> entry : skills.entrySet())
 		{
 			final SkillLearn skill = entry.getValue();
@@ -706,11 +703,6 @@ public class SkillTreeData implements IXmlReader
 				continue;
 			}
 			
-			if (isAwaken && !isCurrentClassSkillNoParent(classId, entry.getKey()) && !isAwakenSaveSkill(player.getClassId(), skill.getSkillId()))
-			{
-				continue;
-			}
-			
 			if (player.getLevel() >= skill.getGetLevel())
 			{
 				if (skill.getSkillLevel() > SkillData.getInstance().getMaxLevel(skill.getSkillId()))
@@ -733,6 +725,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -749,7 +770,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeAutoGet, includeRequiredItems, holder);
@@ -825,20 +846,6 @@ public class SkillTreeData implements IXmlReader
 		}
 		
 		final Race race = player.getRace();
-		final boolean isAwaken = player.isInCategory(CategoryType.SIXTH_CLASS_GROUP);
-		
-		// Race skills
-		if (isAwaken)
-		{
-			for (SkillLearn skill : getRaceSkillTree(race))
-			{
-				if (player.getKnownSkill(skill.getSkillId()) == null)
-				{
-					result.add(skill);
-				}
-			}
-		}
-		
 		for (SkillLearn skill : skills.values())
 		{
 			if (!skill.getRaces().isEmpty() && !skill.getRaces().contains(race))
@@ -846,8 +853,6 @@ public class SkillTreeData implements IXmlReader
 				continue;
 			}
 			
-			final int maxLevel = SkillData.getInstance().getMaxLevel(skill.getSkillId());
-			final long hashCode = SkillData.getSkillHashCode(skill.getSkillId(), maxLevel);
 			if (skill.isAutoGet() && (player.getLevel() >= skill.getGetLevel()))
 			{
 				final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -858,7 +863,7 @@ public class SkillTreeData implements IXmlReader
 						result.add(skill);
 					}
 				}
-				else if (!isAwaken || isCurrentClassSkillNoParent(player.getClassId(), hashCode) || isAwakenSaveSkill(player.getClassId(), skill.getSkillId()))
+				else
 				{
 					result.add(skill);
 				}
@@ -1448,14 +1453,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1465,10 +1471,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1486,6 +1494,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_Classic_Interlude/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_Classic_Interlude/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,13 +16,16 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
+import java.util.Objects;
+import java.util.stream.Collectors;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.data.xml.SkillTreeData;
 import org.l2jmobius.gameserver.model.SkillLearn;
 import org.l2jmobius.gameserver.model.actor.instance.PlayerInstance;
 import org.l2jmobius.gameserver.model.holders.ItemHolder;
+import org.l2jmobius.gameserver.model.skills.Skill;
 import org.l2jmobius.gameserver.network.OutgoingPackets;
 
 /**
@@ -31,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -56,30 +59,26 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		packet.writeH(_learnable.size());
 		for (SkillLearn skill : _learnable)
 		{
-			if (skill == null)
-			{
-				continue;
-			}
-			
 			packet.writeD(skill.getSkillId());
 			packet.writeH(skill.getSkillLevel());
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0x00); // Skill dual class level.
-			if (!skill.getRequiredItems().isEmpty())
+			
+			packet.writeC(skill.getRequiredItems().size());
+			for (ItemHolder item : skill.getRequiredItems())
 			{
-				for (ItemHolder item : skill.getRequiredItems())
+				packet.writeD(item.getId());
-				{
+				packet.writeQ(item.getCount());
-					packet.writeC(0x01);
-					packet.writeD(item.getId());
-					packet.writeQ(item.getCount());
-				}
 			}
-			else
+			
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			packet.writeC(removeSkills.size());
+			for (Skill removed : removeSkills)
 			{
-				packet.writeC(0x00);
+				packet.writeD(removed.getId());
+				packet.writeD(removed.getLevel());
 			}
-			packet.writeC(0x00);
 		}
 		return true;
 	}

L2J_Mobius_Classic_Interlude/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;

L2J_Mobius_Essence_4.2_DwellingOfSpirits/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -270,7 +269,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -664,7 +663,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeAutoGet, true, player);
 	}
@@ -679,9 +678,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -690,7 +689,6 @@ public class SkillTreeData implements IXmlReader
 			return result;
 		}
 		
-		// final boolean isAwaken = player.isInCategory(CategoryType.SIXTH_CLASS_GROUP) && ((player.getRace() != Race.ERTHEIA) || player.isDualClassActive());
 		for (Entry<Long, SkillLearn> entry : skills.entrySet())
 		{
 			final SkillLearn skill = entry.getValue();
@@ -705,10 +703,6 @@ public class SkillTreeData implements IXmlReader
 				continue;
 			}
 			
-			// if (isAwaken && !isCurrentClassSkillNoParent(classId, entry.getKey()) && !isAwakenSaveSkill(player.getClassId(), skill.getSkillId()))
-			// {
-			// continue;
-			// }
 			if (player.getLevel() >= skill.getGetLevel())
 			{
 				if (skill.getSkillLevel() > SkillData.getInstance().getMaxLevel(skill.getSkillId()))
@@ -731,6 +725,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -747,7 +770,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeAutoGet, includeRequiredItems, holder);
@@ -823,19 +846,6 @@ public class SkillTreeData implements IXmlReader
 		}
 		
 		final Race race = player.getRace();
-		// final boolean isAwaken = player.isInCategory(CategoryType.SIXTH_CLASS_GROUP);
-		
-		// Race skills
-		// if (isAwaken)
-		// {
-		// for (SkillLearn skill : getRaceSkillTree(race))
-		// {
-		// if (player.getKnownSkill(skill.getSkillId()) == null)
-		// {
-		// result.add(skill);
-		// }
-		// }
-		// }
 		for (SkillLearn skill : skills.values())
 		{
 			if (!skill.getRaces().isEmpty() && !skill.getRaces().contains(race))
@@ -843,8 +853,6 @@ public class SkillTreeData implements IXmlReader
 				continue;
 			}
 			
-			// final int maxLevel = SkillData.getInstance().getMaxLevel(skill.getSkillId());
-			// final long hashCode = SkillData.getSkillHashCode(skill.getSkillId(), maxLevel);
 			if (skill.isAutoGet() && (player.getLevel() >= skill.getGetLevel()))
 			{
 				final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -855,7 +863,6 @@ public class SkillTreeData implements IXmlReader
 						result.add(skill);
 					}
 				}
-				// else if (!isAwaken || isCurrentClassSkillNoParent(player.getClassId(), hashCode) || isAwakenSaveSkill(player.getClassId(), skill.getSkillId()))
 				else
 				{
 					result.add(skill);
@@ -1446,14 +1453,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1463,10 +1471,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1484,6 +1494,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_Essence_4.2_DwellingOfSpirits/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_Essence_4.2_DwellingOfSpirits/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,13 +16,16 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
+import java.util.Objects;
+import java.util.stream.Collectors;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.data.xml.SkillTreeData;
 import org.l2jmobius.gameserver.model.SkillLearn;
 import org.l2jmobius.gameserver.model.actor.instance.PlayerInstance;
 import org.l2jmobius.gameserver.model.holders.ItemHolder;
+import org.l2jmobius.gameserver.model.skills.Skill;
 import org.l2jmobius.gameserver.network.OutgoingPackets;
 
 /**
@@ -31,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -56,31 +59,27 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		packet.writeH(_learnable.size());
 		for (SkillLearn skill : _learnable)
 		{
-			if (skill == null)
-			{
-				continue;
-			}
-			
 			packet.writeD(skill.getSkillId());
 			packet.writeH(skill.getSkillLevel());
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0x00); // Skill dual class level.
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0x00 : 0x01);
-			if (!skill.getRequiredItems().isEmpty())
+			
+			packet.writeC(skill.getRequiredItems().size());
+			for (ItemHolder item : skill.getRequiredItems())
 			{
-				for (ItemHolder item : skill.getRequiredItems())
+				packet.writeD(item.getId());
-				{
+				packet.writeQ(item.getCount());
-					packet.writeC(0x01);
-					packet.writeD(item.getId());
-					packet.writeQ(item.getCount());
-				}
 			}
-			else
+			
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			packet.writeC(removeSkills.size());
+			for (Skill removed : removeSkills)
 			{
-				packet.writeC(0x00);
+				packet.writeD(removed.getId());
+				packet.writeD(removed.getLevel());
 			}
-			packet.writeC(0x00);
 		}
 		return true;
 	}

L2J_Mobius_Essence_4.2_DwellingOfSpirits/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;

L2J_Mobius_Essence_5.2_FrostLord/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -270,7 +269,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -664,7 +663,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeAutoGet, true, player);
 	}
@@ -679,9 +678,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -690,7 +689,6 @@ public class SkillTreeData implements IXmlReader
 			return result;
 		}
 		
-		// final boolean isAwaken = player.isInCategory(CategoryType.SIXTH_CLASS_GROUP) && ((player.getRace() != Race.ERTHEIA) || player.isDualClassActive());
 		for (Entry<Long, SkillLearn> entry : skills.entrySet())
 		{
 			final SkillLearn skill = entry.getValue();
@@ -705,10 +703,6 @@ public class SkillTreeData implements IXmlReader
 				continue;
 			}
 			
-			// if (isAwaken && !isCurrentClassSkillNoParent(classId, entry.getKey()) && !isAwakenSaveSkill(player.getClassId(), skill.getSkillId()))
-			// {
-			// continue;
-			// }
 			if (player.getLevel() >= skill.getGetLevel())
 			{
 				if (skill.getSkillLevel() > SkillData.getInstance().getMaxLevel(skill.getSkillId()))
@@ -731,6 +725,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -747,7 +770,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeAutoGet, includeRequiredItems, holder);
@@ -823,19 +846,6 @@ public class SkillTreeData implements IXmlReader
 		}
 		
 		final Race race = player.getRace();
-		// final boolean isAwaken = player.isInCategory(CategoryType.SIXTH_CLASS_GROUP);
-		
-		// Race skills
-		// if (isAwaken)
-		// {
-		// for (SkillLearn skill : getRaceSkillTree(race))
-		// {
-		// if (player.getKnownSkill(skill.getSkillId()) == null)
-		// {
-		// result.add(skill);
-		// }
-		// }
-		// }
 		for (SkillLearn skill : skills.values())
 		{
 			if (!skill.getRaces().isEmpty() && !skill.getRaces().contains(race))
@@ -843,8 +853,6 @@ public class SkillTreeData implements IXmlReader
 				continue;
 			}
 			
-			// final int maxLevel = SkillData.getInstance().getMaxLevel(skill.getSkillId());
-			// final long hashCode = SkillData.getSkillHashCode(skill.getSkillId(), maxLevel);
 			if (skill.isAutoGet() && (player.getLevel() >= skill.getGetLevel()))
 			{
 				final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -855,7 +863,6 @@ public class SkillTreeData implements IXmlReader
 						result.add(skill);
 					}
 				}
-				// else if (!isAwaken || isCurrentClassSkillNoParent(player.getClassId(), hashCode) || isAwakenSaveSkill(player.getClassId(), skill.getSkillId()))
 				else
 				{
 					result.add(skill);
@@ -1446,14 +1453,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1463,10 +1471,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1484,6 +1494,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_Essence_5.2_FrostLord/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_Essence_5.2_FrostLord/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,13 +16,16 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
+import java.util.Objects;
+import java.util.stream.Collectors;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.data.xml.SkillTreeData;
 import org.l2jmobius.gameserver.model.SkillLearn;
 import org.l2jmobius.gameserver.model.actor.instance.PlayerInstance;
 import org.l2jmobius.gameserver.model.holders.ItemHolder;
+import org.l2jmobius.gameserver.model.skills.Skill;
 import org.l2jmobius.gameserver.network.OutgoingPackets;
 
 /**
@@ -31,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -56,31 +59,27 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		packet.writeH(_learnable.size());
 		for (SkillLearn skill : _learnable)
 		{
-			if (skill == null)
-			{
-				continue;
-			}
-			
 			packet.writeD(skill.getSkillId());
 			packet.writeH(skill.getSkillLevel());
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0x00); // Skill dual class level.
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0x00 : 0x01);
-			if (!skill.getRequiredItems().isEmpty())
+			
+			packet.writeC(skill.getRequiredItems().size());
+			for (ItemHolder item : skill.getRequiredItems())
 			{
-				for (ItemHolder item : skill.getRequiredItems())
+				packet.writeD(item.getId());
-				{
+				packet.writeQ(item.getCount());
-					packet.writeC(0x01);
-					packet.writeD(item.getId());
-					packet.writeQ(item.getCount());
-				}
 			}
-			else
+			
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			packet.writeC(removeSkills.size());
+			for (Skill removed : removeSkills)
 			{
-				packet.writeC(0x00);
+				packet.writeD(removed.getId());
+				packet.writeD(removed.getLevel());
 			}
-			packet.writeC(0x00);
 		}
 		return true;
 	}

L2J_Mobius_Essence_5.2_FrostLord/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;

L2J_Mobius_Essence_6.0_BattleChronicle/java/org/l2jmobius/gameserver/data/xml/SkillTreeData.java

@@ -24,7 +24,6 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -270,7 +269,7 @@ public class SkillTreeData implements IXmlReader
 										{
 											final int removeSkillId = parseInteger(attrs, "id");
 											skillLearn.addRemoveSkills(removeSkillId);
-											if (!parseBoolean(attrs, "onlyReplaceByLearn", false))
+											if (!parseBoolean(attrs, "onlyReplaceByLearn", false).booleanValue())
 											{
 												_removeSkillCache.computeIfAbsent(classId, k -> new HashSet<>()).add(removeSkillId);
 											}
@@ -664,7 +663,7 @@ public class SkillTreeData implements IXmlReader
 	 * @param includeAutoGet if {@code true} Auto-Get skills will be included
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	public List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		return getAvailableSkills(player, classId, includeByFs, includeAutoGet, true, player);
 	}
@@ -679,9 +678,9 @@ public class SkillTreeData implements IXmlReader
 	 * @param holder
 	 * @return all available skills for a given {@code player}, {@code classId}, {@code includeByFs} and {@code includeAutoGet}
 	 */
-	private List<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
+	private Collection<SkillLearn> getAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet, boolean includeRequiredItems, ISkillsHolder holder)
 	{
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		final Map<Long, SkillLearn> skills = getCompleteClassSkillTree(classId);
 		if (skills.isEmpty())
 		{
@@ -690,7 +689,6 @@ public class SkillTreeData implements IXmlReader
 			return result;
 		}
 		
-		// final boolean isAwaken = player.isInCategory(CategoryType.SIXTH_CLASS_GROUP) && ((player.getRace() != Race.ERTHEIA) || player.isDualClassActive());
 		for (Entry<Long, SkillLearn> entry : skills.entrySet())
 		{
 			final SkillLearn skill = entry.getValue();
@@ -705,10 +703,6 @@ public class SkillTreeData implements IXmlReader
 				continue;
 			}
 			
-			// if (isAwaken && !isCurrentClassSkillNoParent(classId, entry.getKey()) && !isAwakenSaveSkill(player.getClassId(), skill.getSkillId()))
-			// {
-			// continue;
-			// }
 			if (player.getLevel() >= skill.getGetLevel())
 			{
 				if (skill.getSkillLevel() > SkillData.getInstance().getMaxLevel(skill.getSkillId()))
@@ -731,6 +725,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	
@@ -747,7 +770,7 @@ public class SkillTreeData implements IXmlReader
 	{
 		final PlayerSkillHolder holder = new PlayerSkillHolder(player);
 		final Set<Integer> removed = new HashSet<>();
-		List<SkillLearn> learnable;
+		Collection<SkillLearn> learnable;
 		for (int i = 0; i < 1000; i++)
 		{
 			learnable = getAvailableSkills(player, classId, includeByFs, includeAutoGet, includeRequiredItems, holder);
@@ -823,19 +846,6 @@ public class SkillTreeData implements IXmlReader
 		}
 		
 		final Race race = player.getRace();
-		// final boolean isAwaken = player.isInCategory(CategoryType.SIXTH_CLASS_GROUP);
-		
-		// Race skills
-		// if (isAwaken)
-		// {
-		// for (SkillLearn skill : getRaceSkillTree(race))
-		// {
-		// if (player.getKnownSkill(skill.getSkillId()) == null)
-		// {
-		// result.add(skill);
-		// }
-		// }
-		// }
 		for (SkillLearn skill : skills.values())
 		{
 			if (!skill.getRaces().isEmpty() && !skill.getRaces().contains(race))
@@ -843,8 +853,6 @@ public class SkillTreeData implements IXmlReader
 				continue;
 			}
 			
-			// final int maxLevel = SkillData.getInstance().getMaxLevel(skill.getSkillId());
-			// final long hashCode = SkillData.getSkillHashCode(skill.getSkillId(), maxLevel);
 			if (skill.isAutoGet() && (player.getLevel() >= skill.getGetLevel()))
 			{
 				final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -855,7 +863,6 @@ public class SkillTreeData implements IXmlReader
 						result.add(skill);
 					}
 				}
-				// else if (!isAwaken || isCurrentClassSkillNoParent(player.getClassId(), hashCode) || isAwakenSaveSkill(player.getClassId(), skill.getSkillId()))
 				else
 				{
 					result.add(skill);
@@ -1446,14 +1453,15 @@ public class SkillTreeData implements IXmlReader
 		return minLevel;
 	}
 	
-	public List<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
+	public Collection<SkillLearn> getNextAvailableSkills(PlayerInstance player, ClassId classId, boolean includeByFs, boolean includeAutoGet)
 	{
 		final Map<Long, SkillLearn> completeClassSkillTree = getCompleteClassSkillTree(classId);
-		final List<SkillLearn> result = new LinkedList<>();
+		final Set<SkillLearn> result = ConcurrentHashMap.newKeySet();
 		if (completeClassSkillTree.isEmpty())
 		{
 			return result;
 		}
+		
 		final int minLevelForNewSkill = getMinLevelForNewSkill(player, completeClassSkillTree);
 		if (minLevelForNewSkill > 0)
 		{
@@ -1463,10 +1471,12 @@ public class SkillTreeData implements IXmlReader
 				{
 					continue;
 				}
+				
 				if ((!includeAutoGet && skill.isAutoGet()) || (!includeByFs && skill.isLearnedByFS()))
 				{
 					continue;
 				}
+				
 				if (minLevelForNewSkill <= skill.getGetLevel())
 				{
 					final Skill oldSkill = player.getKnownSkill(skill.getSkillId());
@@ -1484,6 +1494,35 @@ public class SkillTreeData implements IXmlReader
 				}
 			}
 		}
+		
+		// Manage skill unlearn.
+		for (Skill knownSkill : player.getSkillList())
+		{
+			final SkillLearn skillLearn = getClassSkill(knownSkill.getId(), knownSkill.getLevel(), classId);
+			if (skillLearn == null)
+			{
+				continue;
+			}
+			
+			final Set<Integer> removeSkills = skillLearn.getRemoveSkills();
+			if (removeSkills.isEmpty())
+			{
+				continue;
+			}
+			
+			for (Integer removeId : removeSkills)
+			{
+				SEARCH: for (SkillLearn knownLearn : result)
+				{
+					if (knownLearn.getSkillId() == removeId.intValue())
+					{
+						result.remove(knownLearn);
+						break SEARCH;
+					}
+				}
+			}
+		}
+		
 		return result;
 	}
 	

L2J_Mobius_Essence_6.0_BattleChronicle/java/org/l2jmobius/gameserver/model/actor/instance/NpcInstance.java

@@ -16,6 +16,7 @@
  */
 package org.l2jmobius.gameserver.model.actor.instance;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -86,7 +87,7 @@ public class NpcInstance extends Npc
 		}
 		
 		// Normal skills, No LearnedByFS, no AutoGet skills.
-		final List<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
+		final Collection<SkillLearn> skills = SkillTreeData.getInstance().getAvailableSkills(player, classId, false, false);
 		if (skills.isEmpty())
 		{
 			final Map<Long, SkillLearn> skillTree = SkillTreeData.getInstance().getCompleteClassSkillTree(classId);

L2J_Mobius_Essence_6.0_BattleChronicle/java/org/l2jmobius/gameserver/network/serverpackets/AcquireSkillList.java

@@ -16,13 +16,16 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
+import java.util.Objects;
+import java.util.stream.Collectors;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.data.xml.SkillTreeData;
 import org.l2jmobius.gameserver.model.SkillLearn;
 import org.l2jmobius.gameserver.model.actor.instance.PlayerInstance;
 import org.l2jmobius.gameserver.model.holders.ItemHolder;
+import org.l2jmobius.gameserver.model.skills.Skill;
 import org.l2jmobius.gameserver.network.OutgoingPackets;
 
 /**
@@ -31,7 +34,7 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
 public class AcquireSkillList implements IClientOutgoingPacket
 {
 	private PlayerInstance _player;
-	private List<SkillLearn> _learnable;
+	private Collection<SkillLearn> _learnable;
 	
 	public AcquireSkillList(PlayerInstance player)
 	{
@@ -56,31 +59,27 @@ public class AcquireSkillList implements IClientOutgoingPacket
 		packet.writeH(_learnable.size());
 		for (SkillLearn skill : _learnable)
 		{
-			if (skill == null)
-			{
-				continue;
-			}
-			
 			packet.writeD(skill.getSkillId());
 			packet.writeH(skill.getSkillLevel());
 			packet.writeQ(skill.getLevelUpSp());
 			packet.writeC(skill.getGetLevel());
 			packet.writeC(0x00); // Skill dual class level.
 			packet.writeC(_player.getKnownSkill(skill.getSkillId()) != null ? 0x00 : 0x01);
-			if (!skill.getRequiredItems().isEmpty())
+			
+			packet.writeC(skill.getRequiredItems().size());
+			for (ItemHolder item : skill.getRequiredItems())
 			{
-				for (ItemHolder item : skill.getRequiredItems())
+				packet.writeD(item.getId());
-				{
+				packet.writeQ(item.getCount());
-					packet.writeC(0x01);
-					packet.writeD(item.getId());
-					packet.writeQ(item.getCount());
-				}
 			}
-			else
+			
+			final Collection<Skill> removeSkills = skill.getRemoveSkills().stream().map(_player::getKnownSkill).filter(Objects::nonNull).collect(Collectors.toList());
+			packet.writeC(removeSkills.size());
+			for (Skill removed : removeSkills)
 			{
-				packet.writeC(0x00);
+				packet.writeD(removed.getId());
+				packet.writeD(removed.getLevel());
 			}
-			packet.writeC(0x00);
 		}
 		return true;
 	}

L2J_Mobius_Essence_6.0_BattleChronicle/java/org/l2jmobius/gameserver/network/serverpackets/ExAcquirableSkillListByClass.java

@@ -16,7 +16,7 @@
  */
 package org.l2jmobius.gameserver.network.serverpackets;
 
-import java.util.List;
+import java.util.Collection;
 
 import org.l2jmobius.commons.network.PacketWriter;
 import org.l2jmobius.gameserver.enums.AcquireSkillType;
@@ -28,10 +28,10 @@ import org.l2jmobius.gameserver.network.OutgoingPackets;
  */
 public class ExAcquirableSkillListByClass implements IClientOutgoingPacket
 {
-	final List<SkillLearn> _learnable;
+	private final Collection<SkillLearn> _learnable;
-	final AcquireSkillType _type;
+	private final AcquireSkillType _type;
 	
-	public ExAcquirableSkillListByClass(List<SkillLearn> learnable, AcquireSkillType type)
+	public ExAcquirableSkillListByClass(Collection<SkillLearn> learnable, AcquireSkillType type)
 	{
 		_learnable = learnable;
 		_type = type;