Capability

CapabilityWhistleableEntity.java

package com.leviathan143.dogwhistle.api.whistle;

import java.util.concurrent.Callable;

import net.minecraft.nbt.NBTBase;
import net.minecraft.util.EnumFacing;
import net.minecraftforge.common.capabilities.Capability;
import net.minecraftforge.common.capabilities.CapabilityInject;
import net.minecraftforge.common.capabilities.CapabilityManager;

public class CapabilityWhistleableEntity 
{
	@CapabilityInject(IWhistleableEntity.class)
	public static Capability<IWhistleableEntity> CAP_WHISTLEABLE_ENTITY = null;
	
	public static void register()
	{
		CapabilityManager.INSTANCE.register(IWhistleableEntity.class, new Capability.IStorage<IWhistleableEntity>() 
		{
			@Override
			public NBTBase writeNBT(Capability<IWhistleableEntity> capability,
					IWhistleableEntity instance, EnumFacing side) {return null;}

			@Override
			public void readNBT(Capability<IWhistleableEntity> capability, IWhistleableEntity instance, EnumFacing side, NBTBase nbt) {}
		}, 
		new Callable<IWhistleableEntity>() 
		{
			@Override
			public IWhistleableEntity call() throws Exception {return null;}
		});
	}
}

IWhistleableEntity.java

package com.leviathan143.dogwhistle.api.whistle;

import net.minecraft.entity.Entity;

public interface IWhistleableEntity 
{
	public void sit(Entity entity);
}

VanillaEntityCapAttacher.java

package com.leviathan143.dogwhistle.common.capability;

import net.minecraft.entity.passive.EntityWolf;
import net.minecraftforge.event.AttachCapabilitiesEvent;
import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;

public class VanillaEntityCapAttacher 
{
	@SubscribeEvent
	public static void attachCaps(AttachCapabilitiesEvent.Entity event)
	{
		if(event.getEntity() instanceof EntityWolf)
		{
			event.addCapability(WolfWhistleHandler.CAP_KEY, WolfWhistleHandler.INSTANCE);
		}
	}
}

WolfWhistleHandler.java

package com.leviathan143.dogwhistle.common.capability;

import net.minecraft.entity.Entity;
import net.minecraft.entity.passive.EntityWolf;
import net.minecraft.util.EnumFacing;
import net.minecraft.util.ResourceLocation;
import net.minecraftforge.common.capabilities.Capability;
import net.minecraftforge.common.capabilities.ICapabilityProvider;

import com.leviathan143.dogwhistle.api.whistle.CapabilityWhistleableEntity;
import com.leviathan143.dogwhistle.api.whistle.IWhistleableEntity;
import com.leviathan143.dogwhistle.api.whistle.Whistle;
import com.leviathan143.dogwhistle.common.DogWhistleMain.Constants;

public class WolfWhistleHandler implements ICapabilityProvider
{
	public static final ResourceLocation CAP_KEY = new ResourceLocation(Constants.MODID, "wolfWhistle");
	public static final WolfWhistleHandler INSTANCE = new WolfWhistleHandler();
	
	@Override
	public boolean hasCapability(Capability<?> capability, EnumFacing facing) 
	{
		if(capability == CapabilityWhistleableEntity.CAP_WHISTLEABLE_ENTITY) 
			{
				return true;
			}
		return false;
	}

	@Override
	public <T> T getCapability(Capability<T> capability, EnumFacing facing) 
	{
		if(capability == CapabilityWhistleableEntity.CAP_WHISTLEABLE_ENTITY) return (T) WolfWhistleCap.INSTANCE;
		return null;
	}
	
	public static class WolfWhistleCap implements IWhistleableEntity
	{
		public static final WolfWhistleCap INSTANCE = new WolfWhistleCap();
		
		@Override
		public void sit(Entity entity) 
		{
			((EntityWolf)entity).getAISit().setSitting(true);
		}
	}
}