[1.12.2] Using Event Hooks to spawn entity

Lea9ue · August 22, 2019

Code works as is, but cant get a Entity to spawn in a static event. Am I missing something? What I am trying to achieve is when an entity dies, it checks to see what entity was killed and then what entity did the killing. If it was Zombie that did the killing, I would like to spawn another ZombieEntity in the place of the dead entity. Any other way of doing this that im not thinking of?

ServerEventZombieKill.class:

{

	@SubscribeEvent

	public static void onDeath(LivingDeathEvent event)
		{
		if (event.getEntity() instanceof EntityZombie) 
			{
			System.out.println("Zombie");
			}
		if (event.getEntity() instanceof EntitySkeleton) 
		{
			System.out.println("Skeleton");
			if (event.getSource().getTrueSource() instanceof EntityZombie) {
				System.out.println("Skeleton killed by Zombie");
			}
		}			
	}

Main:

@EventHandler
public void init2(FMLPreInitializationEvent event) {
    MinecraftForge.EVENT_BUS.register(ServerEventZombieKill.class);

I can get the outcome I want in my custom entity class like this:

@Override
	public void onKillEntity(EntityLivingBase entityLivingIn)
	{
		if (entityLivingIn instanceof IMob)
		{
			System.out.println("Mob");
			
           EntityWalker walker = new EntityWalker(this.world);
           walker.setLocationAndAngles(entityLivingIn.posX, entityLivingIn.posY, entityLivingIn.posZ, 0, 0);
        		if (!entityLivingIn.world.isRemote) { 
        			this.world.spawnEntity(walker);
			}
		}
	}

^^^^ But obviously I cant do that method to Vanilla Entities.

Lea9ue · August 22, 2019

In my first code example I can get it to work only if I use public static void. Public void I'm assuming doesn't work since I'm not getting messages in Console (eclipse). The spawning code EntityZombie zombie = new EntityZombie(this.world); I used in the third example is typically what I would use when spawning a entity but I cant use (this.world) in a static class (public static void). For setting Location of spawn I'm trying to use zombie.setLocationAndAngles(event.getSource().getTrueSource().posX, event.getSource().getTrueSource().posY, event.getSource().getTrueSource().posZ, 0, 0); which I believe should work fine. Then for the actual spawning typically I would use this.world.spawnEntity(zombie);

So the over all code that I'm stuck with is

	@SubscribeEvent

	public void onDeath(LivingDeathEvent event)
		{
		if (event.getEntity() instanceof EntitySkeleton) 
		{
			if (event.getSource().getTrueSource() instanceof EntityZombie) {
				EntityZombie zombie = new EntityZombie(//NO IDEA WHAT TO PUT HERE//);
				zombie.setLocationAndAngles(event.getSource().getTrueSource().posX, event.getSource().getTrueSource().posY, event.getSource().getTrueSource().posZ,0,0);
				(///NO IDEA WHAT TO PUT HERE///).spawnEntity(walker);
				
				
				
			}
		}			
	}

So as you can see, my amateur java brain can't seem to grasp what to do. I think I'm atleast close. Any advice would be appreciated.

Animefan8888 · August 22, 2019

4 minutes ago, Lea9ue said:

//NO IDEA WHAT TO PUT HERE//

I wonder if the event has a solution to this. Or if the entities that I have access to(The dying entity and the damager) have access to the world they are in like my entity.

Lea9ue · August 22, 2019

I don't know. Yes I get that the entities have access to the world they are In . I'm just not smart enough to implement it. Heres what code looks like but it crashes when entity spawns

private static World worldIn;

	@SubscribeEvent

	public static void onDeath(LivingDeathEvent event)
		{

		if (event.getEntity() instanceof EntityZombie) 
			{
			System.out.println("Zombie");
			}
		if (event.getEntity() instanceof EntitySkeleton) 
		{
			System.out.println("Skeleton");
			if (event.getSource().getTrueSource() instanceof EntityZombie) {
				System.out.println("Skeleton killed by Zombie");
				
				EntityZombie zombie = new EntityZombie(worldIn);
				zombie.setLocationAndAngles(event.getSource().getTrueSource().posX,event.getSource().getTrueSource().posY,event.getSource().getTrueSource().posZ,0,0); 
				worldIn.spawnEntity(zombie);
				
				
				
			}
		}			
	}

Animefan8888 · August 22, 2019

1 minute ago, Lea9ue said:

Heres what code looks like but it crashes

Well can't help if I don't have the crash report.

Lea9ue · August 22, 2019

5 minutes ago, Animefan8888 said:

Well can't help if I don't have the crash report.

My Fault

Crash Report:

---- Minecraft Crash Report ----
// Don't be sad, have a hug! <3

Time: 8/22/19 5:30 PM
Description: Ticking entity

java.lang.NullPointerException: Ticking entity
	at com.lea9ue.mobwars.server.ServerEventWalkerKill.onDeath(ServerEventWalkerKill.java:42)
	at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_13_ServerEventWalkerKill_onDeath_LivingDeathEvent.invoke(.dynamic)
	at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90)
	at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:182)
	at net.minecraftforge.common.ForgeHooks.onLivingDeath(ForgeHooks.java:601)
	at net.minecraft.entity.EntityLivingBase.onDeath(EntityLivingBase.java:1284)
	at net.minecraft.entity.monster.EntitySkeleton.onDeath(EntitySkeleton.java:62)
	at net.minecraft.entity.EntityLivingBase.attackEntityFrom(EntityLivingBase.java:1129)
	at net.minecraft.entity.monster.EntityMob.attackEntityFrom(EntityMob.java:80)
	at net.minecraft.entity.monster.EntityMob.attackEntityAsMob(EntityMob.java:109)
	at net.minecraft.entity.monster.EntityZombie.attackEntityAsMob(EntityZombie.java:320)
	at net.minecraft.entity.ai.EntityAIAttackMelee.checkAndPerformAttack(EntityAIAttackMelee.java:197)
	at net.minecraft.entity.ai.EntityAIAttackMelee.updateTask(EntityAIAttackMelee.java:186)
	at net.minecraft.entity.ai.EntityAIZombieAttack.updateTask(EntityAIZombieAttack.java:39)
	at net.minecraft.entity.ai.EntityAITasks.onUpdateTasks(EntityAITasks.java:114)
	at net.minecraft.entity.EntityLiving.updateEntityActionState(EntityLiving.java:843)
	at net.minecraft.entity.EntityLivingBase.onLivingUpdate(EntityLivingBase.java:2582)
	at net.minecraft.entity.EntityLiving.onLivingUpdate(EntityLiving.java:647)
	at net.minecraft.entity.monster.EntityMob.onLivingUpdate(EntityMob.java:49)
	at net.minecraft.entity.monster.EntityZombie.onLivingUpdate(EntityZombie.java:246)
	at net.minecraft.entity.EntityLivingBase.onUpdate(EntityLivingBase.java:2398)
	at net.minecraft.entity.EntityLiving.onUpdate(EntityLiving.java:346)
	at net.minecraft.entity.monster.EntityMob.onUpdate(EntityMob.java:57)
	at net.minecraft.world.World.updateEntityWithOptionalForce(World.java:2171)
	at net.minecraft.world.WorldServer.updateEntityWithOptionalForce(WorldServer.java:871)
	at net.minecraft.world.World.updateEntity(World.java:2130)
	at net.minecraft.world.World.updateEntities(World.java:1931)
	at net.minecraft.world.WorldServer.updateEntities(WorldServer.java:643)
	at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:842)
	at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:743)
	at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:192)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:592)
	at java.lang.Thread.run(Unknown Source)


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Thread: Server thread
Stacktrace:
	at com.lea9ue.mobwars.server.ServerEventWalkerKill.onDeath(ServerEventWalkerKill.java:42)
	at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_13_ServerEventWalkerKill_onDeath_LivingDeathEvent.invoke(.dynamic)
	at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90)
	at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:182)
	at net.minecraftforge.common.ForgeHooks.onLivingDeath(ForgeHooks.java:601)
	at net.minecraft.entity.EntityLivingBase.onDeath(EntityLivingBase.java:1284)
	at net.minecraft.entity.monster.EntitySkeleton.onDeath(EntitySkeleton.java:62)
	at net.minecraft.entity.EntityLivingBase.attackEntityFrom(EntityLivingBase.java:1129)
	at net.minecraft.entity.monster.EntityMob.attackEntityFrom(EntityMob.java:80)
	at net.minecraft.entity.monster.EntityMob.attackEntityAsMob(EntityMob.java:109)
	at net.minecraft.entity.monster.EntityZombie.attackEntityAsMob(EntityZombie.java:320)
	at net.minecraft.entity.ai.EntityAIAttackMelee.checkAndPerformAttack(EntityAIAttackMelee.java:197)
	at net.minecraft.entity.ai.EntityAIAttackMelee.updateTask(EntityAIAttackMelee.java:186)
	at net.minecraft.entity.ai.EntityAIZombieAttack.updateTask(EntityAIZombieAttack.java:39)
	at net.minecraft.entity.ai.EntityAITasks.onUpdateTasks(EntityAITasks.java:114)
	at net.minecraft.entity.EntityLiving.updateEntityActionState(EntityLiving.java:843)
	at net.minecraft.entity.EntityLivingBase.onLivingUpdate(EntityLivingBase.java:2582)
	at net.minecraft.entity.EntityLiving.onLivingUpdate(EntityLiving.java:647)
	at net.minecraft.entity.monster.EntityMob.onLivingUpdate(EntityMob.java:49)
	at net.minecraft.entity.monster.EntityZombie.onLivingUpdate(EntityZombie.java:246)
	at net.minecraft.entity.EntityLivingBase.onUpdate(EntityLivingBase.java:2398)
	at net.minecraft.entity.EntityLiving.onUpdate(EntityLiving.java:346)
	at net.minecraft.entity.monster.EntityMob.onUpdate(EntityMob.java:57)
	at net.minecraft.world.World.updateEntityWithOptionalForce(World.java:2171)
	at net.minecraft.world.WorldServer.updateEntityWithOptionalForce(WorldServer.java:871)
	at net.minecraft.world.World.updateEntity(World.java:2130)

-- Entity being ticked --
Details:
	Entity Type: minecraft:zombie (net.minecraft.entity.monster.EntityZombie)
	Entity ID: 24633
	Entity Name: Zombie
	Entity's Exact location: -62.46, 202.00, -38.73
	Entity's Block location: World: (-63,202,-39), Chunk: (at 1,12,9 in -4,-3; contains blocks -64,0,-48 to -49,255,-33), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
	Entity's Momentum: 0.00, -0.08, -0.06
	Entity's Passengers: []
	Entity's Vehicle: ~~ERROR~~ NullPointerException: null
Stacktrace:
	at net.minecraft.world.World.updateEntities(World.java:1931)
	at net.minecraft.world.WorldServer.updateEntities(WorldServer.java:643)

-- Affected level --
Details:
	Level name: New World
	All players: 1 total; [EntityPlayerMP['Player517'/598, l='New World', x=-58.45, y=203.04, z=-38.26]]
	Chunk stats: ServerChunkCache: 767 Drop: 0
	Level seed: 6659549246155252085
	Level generator: ID 00 - default, ver 1. Features enabled: true
	Level generator options: 
	Level spawn location: World: (116,64,88), Chunk: (at 4,4,8 in 7,5; contains blocks 112,0,80 to 127,255,95), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Level time: 98358 game time, 21320 day time
	Level dimension: 0
	Level storage version: 0x04ABD - Anvil
	Level weather: Rain time: 39332 (now: false), thunder time: 70297 (now: false)
	Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: true
Stacktrace:
	at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:842)
	at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:743)
	at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:192)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:592)
	at java.lang.Thread.run(Unknown Source)

-- System Details --
Details:
	Minecraft Version: 1.12.2
	Operating System: Windows 10 (amd64) version 10.0
	Java Version: 1.8.0_221, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 728052120 bytes (694 MB) / 1037959168 bytes (989 MB) up to 1037959168 bytes (989 MB)
	JVM Flags: 3 total; -Xincgc -Xmx1024M -Xms1024M
	IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
	FML: MCP 9.42 Powered by Forge 14.23.5.2768 5 mods loaded, 5 mods active
	States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored

	| State     | ID        | Version      | Source                           | Signature |
	|:--------- |:--------- |:------------ |:-------------------------------- |:--------- |
	| UCHIJAAAA | minecraft | 1.12.2       | minecraft.jar                    | None      |
	| UCHIJAAAA | mcp       | 9.42         | minecraft.jar                    | None      |
	| UCHIJAAAA | FML       | 8.0.99.99    | forgeSrc-1.12.2-14.23.5.2768.jar | None      |
	| UCHIJAAAA | forge     | 14.23.5.2768 | forgeSrc-1.12.2-14.23.5.2768.jar | None      |
	| UCHIJAAAA | mobwars   | 0.1.0        | bin                              | None      |

	Loaded coremods (and transformers): 
	GL info: ~~ERROR~~ RuntimeException: No OpenGL context found in the current thread.
	Profiler Position: N/A (disabled)
	Player Count: 1 / 8; [EntityPlayerMP['Player517'/598, l='New World', x=-58.45, y=203.04, z=-38.26]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Definitely; Client brand changed to 'fml,forge'

Edited August 22, 2019 by Lea9ue

Animefan8888 · August 22, 2019

1 minute ago, Lea9ue said:

at com.lea9ue.mobwars.server.ServerEventWalkerKill.onDeath(ServerEventWalkerKill.java:36)

What is line 36?

Lea9ue · August 23, 2019

3 hours ago, diesieben07 said:

No. Why?

Oh, I know why: You just typed "worldIn" and Eclipse told you that doesn't exist. It's suggested quick-fix of "create static field" is not appropriate here.

Learn Java. Programming by repeatedly and blindly applying Eclipse's quick-fixes does not work.

I am aware that this is the problem and that my lack of java knowledge isn't helping the situation. As I said in my 2nd post, I have no idea what to do there. So thanks for the suggestion of not using quick-fixes, is there a direction you can point me in to get me on the right track?

Lea9ue · August 23, 2019

17 minutes ago, diesieben07 said:

Thank you, should of read into that more yesterday. Current code works without crashing here:

@SubscribeEvent

	public static void onDeath(LivingDeathEvent event)
		{
		
		World world = event.getEntityLiving().world;

		if (event.getEntity() instanceof EntityZombie) 
			{
			System.out.println("Zombie");
			}
		if (event.getEntity() instanceof EntitySkeleton) 
		{
			System.out.println("Skeleton");
			if (event.getSource().getTrueSource() instanceof EntityZombie) {
				System.out.println("Skeleton killed by Zombie");
	
				EntityZombie zombie = new EntityZombie(world);
				zombie.setLocationAndAngles(event.getSource().getTrueSource().posX, 
						event.getSource().getTrueSource().posY,	event.getSource().getTrueSource().posZ,	0, 0); 
				world.spawnEntity(zombie);
				
				
				
			}
		}			
	}

Is there a better way of getting it? Just want to learn.

DavidM · August 23, 2019

~~Your code is not going to work as intended.~~

~~Your code will run whenever a skeleton dies instead of when killed by a zombie.~~

Oops I missed that.

Also, might as will move the getting of the World instance inside your if.

Edited August 24, 2019 by DavidM

CAS_ual_TY · August 23, 2019

No. The code IS run when a skeleton dies to a zombie. There are more than 2 if brackets. Or am I missing smth here?

Animefan8888 · August 23, 2019

3 hours ago, DavidM said:

Your code will run whenever a skeleton dies instead of when killed by a zombie

It will they have a print line in the first one, but in the one where they check for the skeleton there is another if statement inside to check if the attacker is a Zombie.

Lea9ue · August 23, 2019

4 hours ago, DavidM said:

Your code is not going to work as intended.

Your code will run whenever a skeleton dies instead of when killed by a zombie.

Hide contents

Your second if is not in your first if.

Also, might as will move the getting of the World instance inside your if.

Everything is working as wanted. Checking for instance of zombie at first is not needed and might of confused. I was only doing that so when I tested and spawned in zombie and skeleton, if skeleton was the victor I would still know right away that code was working up to that point.

Hopefully my last question, in this case, do I need to check if world is remote before spawning entity? example:

if (!world.isRemote) {
	world.spawnEntity(zombie);
	}

or is it just redundant at that point in time?

Animefan8888 · August 23, 2019

40 minutes ago, Lea9ue said:

or is it just redundant at that point in time?

I think it is redundant because that event is only fired on the server.

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[1.12.2] Using Event Hooks to spawn entity

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