Entity AI Task Issue

[WillR27398]

So I want my entity to be able to swap out its AI so that it can go from doing one thing to another, however, in doing this it seems to cause a ConcurrentModificationException:

 

at java.util.LinkedHashMap$LinkedHashIterator.nextNode(LinkedHashMap.java:719)
at java.util.LinkedHashMap$LinkedKeyIterator.next(LinkedHashMap.java:742)
at net.minecraft.entity.ai.EntityAITasks.onUpdateTasks(EntityAITasks.java:70)
at net.minecraft.entity.EntityLiving.updateEntityActionState(EntityLiving.java:846)
at net.minecraft.entity.EntityLivingBase.onLivingUpdate(EntityLivingBase.java:2470)
at net.minecraft.entity.EntityLiving.onLivingUpdate(EntityLiving.java:640)
at net.minecraft.entity.EntityAgeable.onLivingUpdate(EntityAgeable.java:194)
at net.minecraft.entity.passive.EntityAnimal.onLivingUpdate(EntityAnimal.java:46)
at willr27.blocklings.entity.EntityBlockling.onLivingUpdate(EntityBlockling.java:894)
at net.minecraft.entity.EntityLivingBase.onUpdate(EntityLivingBase.java:2296)
at net.minecraft.entity.EntityLiving.onUpdate(EntityLiving.java:344)
at net.minecraft.world.World.updateEntityWithOptionalForce(World.java:2117)
at net.minecraft.world.WorldServer.updateEntityWithOptionalForce(WorldServer.java:876)
at net.minecraft.world.World.updateEntity(World.java:2083)

 

I can never get this to replicate consistently so seems somewhat random to me at the moment. Just wondering if anyone has come across this before? I'm just using addTask(...) and removeTask(...) to add and remove the AI.

[jeffryfisher]

I think it would be better to line up your AI tasks in priority order similar to the way vanilla entities do. Then write your logic into the tasks' should-run and should-continue methods. I think those are what decide whether a particular AI task should "swap out" so something else can run. In other words, AI tasks shouldn't be unplugged, they should merely give up control.

Edited April 19, 2017 by jeffryfisher

[WillR27398]

Okay, I sort of figured as much, but wasn't too sure whether there was a way around it or not. I will just redo some of the logic then in the AI code, thanks.

[Draco18s]

You shouldn't modify the task list. You should instead have tasks return false from canExecute.