I've been struggling with how to make it so that when you equip all 4 pieces of a set of armor, you get a potion effect. I had it working back in 1.7.10, but the updates in 1.8 and up have changed the way things work. I tried a few other ideas, but it just doesn't seem to work. Can anyone help? This is my armor class:

 

package sureen.core.armor;

import net.minecraft.entity.Entity;
import net.minecraft.entity.EntityLivingBase;
import net.minecraft.inventory.EntityEquipmentSlot;
import net.minecraft.item.ItemArmor;
import net.minecraft.item.ItemStack;
import net.minecraft.potion.Potion;
import net.minecraft.potion.PotionEffect;
import net.minecraft.world.World;
import sureen.core.SureenCore;
import sureen.core.registry.SureenItems;

public class CrystalArmor extends ItemArmor {

public CrystalArmor(int renderIndex, EntityEquipmentSlot slot){
	super(SureenCore.CrystalArmor, renderIndex, slot);		
}

public void OnUpdate(ItemStack item, World world, Entity entity, int itemSlot, boolean isSelected){
	if(entity instanceof EntityLivingBase){
		EntityLivingBase livingBase = (EntityLivingBase) entity;
		if(livingBase.getItemStackFromSlot(EntityEquipmentSlot.HEAD) != null && livingBase.getItemStackFromSlot(EntityEquipmentSlot.CHEST) != null && livingBase.getItemStackFromSlot(EntityEquipmentSlot.LEGS) != null && livingBase.getItemStackFromSlot(EntityEquipmentSlot.FEET) != null){
			ItemStack helmet = livingBase.getItemStackFromSlot(EntityEquipmentSlot.HEAD);
			ItemStack chestplate = livingBase.getItemStackFromSlot(EntityEquipmentSlot.CHEST);
			ItemStack leggings = livingBase.getItemStackFromSlot(EntityEquipmentSlot.LEGS);
			ItemStack boots = livingBase.getItemStackFromSlot(EntityEquipmentSlot.FEET);
			System.out.println(helmet + " " + chestplate + " " + leggings + " " + boots);

			if (helmet.getItem() == SureenItems.crystal_helmet && chestplate.getItem() == SureenItems.crystal_chestplate && leggings.getItem() == SureenItems.crystal_leggings && boots.getItem() == SureenItems.crystal_boots){
				((EntityLivingBase) entity).addPotionEffect(new PotionEffect(Potion.getPotionFromResourceLocation("absorption"), 1, 1));
			}
		}
	}
}

}

What is the specific problem? No potion effect at all?

Yeah, it's not putting any potion effect at all. I have absorption in the code because I thought maybe it just wasn't showing the potion effects, but was still applying them, but it didn't give me any absorption hearts, so I can tell it's not applying any effects.

Try putting @Override over your method you should see the error. And if you don't does it print out the ItemStacks?

When I put @Override, I get this: "The method OnUpdate(ItemStack, World, Entity, int, boolean) of type CrystalArmor must override or implement a supertype method" Otherwise, it doesn't even seem to operate at all.

Exactly you are not overriding the "right" method(not any method at all), just a suggestion but whenever you are using a method that you didn't create in that class always put @Override. When it was like that it should not have worked at all in previous versions either.

Odd, well, I've always used the OnArmorTick method (which doesn't seem to work here) and neither does OnUpdate. Any idea which method I should be using here?

Go to ItemArmor and find the onArmorTick method, copy its signature, paste it over your method.

I don't seem to see an onArmorTick method in ItemArmor... I even did a search for it, but it said it wasn't there.

It is actually in Item.

Awesome, it works now! Not sure if this code can be cleaned up further due to the changes made, but this is what I got to work.

package sureen.core.armor;

import net.minecraft.entity.Entity;
import net.minecraft.entity.EntityLivingBase;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.inventory.EntityEquipmentSlot;
import net.minecraft.item.ItemArmor;
import net.minecraft.item.ItemStack;
import net.minecraft.potion.Potion;
import net.minecraft.potion.PotionEffect;
import net.minecraft.world.World;
import sureen.core.SureenCore;
import sureen.core.registry.SureenItems;

public class CrystalArmor extends ItemArmor {

public CrystalArmor(int renderIndex, EntityEquipmentSlot slot){
	super(SureenCore.CrystalArmor, renderIndex, slot);		
}

@Override
public void onArmorTick(World world, EntityPlayer player, ItemStack itemStack){
	if(player instanceof EntityLivingBase){
		EntityLivingBase livingBase = (EntityLivingBase) player;
		if(livingBase.getItemStackFromSlot(EntityEquipmentSlot.HEAD) != null && livingBase.getItemStackFromSlot(EntityEquipmentSlot.CHEST) != null && livingBase.getItemStackFromSlot(EntityEquipmentSlot.LEGS) != null && livingBase.getItemStackFromSlot(EntityEquipmentSlot.FEET) != null){
			ItemStack helmet = livingBase.getItemStackFromSlot(EntityEquipmentSlot.HEAD);
			ItemStack chestplate = livingBase.getItemStackFromSlot(EntityEquipmentSlot.CHEST);
			ItemStack leggings = livingBase.getItemStackFromSlot(EntityEquipmentSlot.LEGS);
			ItemStack boots = livingBase.getItemStackFromSlot(EntityEquipmentSlot.FEET);
			System.out.println(helmet + " " + chestplate + " " + leggings + " " + boots);

			if (helmet.getItem() == SureenItems.crystal_helmet && chestplate.getItem() == SureenItems.crystal_chestplate && leggings.getItem() == SureenItems.crystal_leggings && boots.getItem() == SureenItems.crystal_boots){
				((EntityLivingBase) player).addPotionEffect(new PotionEffect(Potion.getPotionFromResourceLocation("absorption"), 1, 1));
			}
		}
	}
}

}

You could make the variables before checking if they are != null then use them to check if they are not equal to null. Remove the println. That is all I can think of right now, everything else looks good.

Awesome, it works now

 

And now you know that to Override a method you should always let your IDE do it or find the method you want to override and copy it, and then never touch its signature.