What happens is right now when holding the gemstone it gives the holder regeneration 2, however at the moment the timer doesn't tick down, making it so that the player doesn't actually regenerate, how do I fix this?

 

package com.Recable.mod.gemstones;

import java.util.List;

import com.Recable.mod.ModGlobal;

import net.minecraft.enchantment.Enchantment;
import net.minecraft.enchantment.EnchantmentHelper;
import net.minecraft.entity.Entity;
import net.minecraft.entity.EntityLivingBase;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.entity.projectile.EntityArrow;
import net.minecraft.init.Items;
import net.minecraft.item.EnumAction;
import net.minecraft.item.Item;
import net.minecraft.item.Item.ToolMaterial;
import net.minecraft.item.ItemPickaxe;
import net.minecraft.item.ItemStack;
import net.minecraft.potion.Potion;
import net.minecraft.potion.PotionEffect;
import net.minecraft.stats.StatList;
import net.minecraft.world.World;

public class ModVitalityGemstone extends Item {

public ModVitalityGemstone(String unlocalizedName) {
	super();
	this.setUnlocalizedName(unlocalizedName);
	this.setCreativeTab(ModGlobal.ModCreativeTabGemstones);
	this.setMaxStackSize(1);
}

@Override
public void onUpdate(ItemStack stack, World worldIn, Entity entity, int i, boolean flag) {
	if (entity instanceof EntityPlayer) {          
    	  EntityPlayer Player = (EntityPlayer) entity;
          if(Player.getCurrentEquippedItem() != null && Player.getCurrentEquippedItem().getItem() instanceof ModVitalityGemstone) {
        	  Player.addPotionEffect(new PotionEffect(Potion.regeneration.id, 50, 2 - 1));
        	  Player.removePotionEffect(i);
          }
          else {
        	  Player.removePotionEffect(i);
          }
	}
}
	private void effectPlayer(Entity entityIn, Potion potion, int amplifier) {

		EntityLivingBase player = (EntityLivingBase) entityIn;
		if (player.getActivePotionEffect(potion)== null || player.getActivePotionEffect(potion).getDuration() <=20)
			player.addPotionEffect(new PotionEffect(potion.id, 40 /** Duration */, amplifier, true, true));
}

Use

EntityLivingBase#isPotionActive(Potion)

to ensure the potion isn't already active before applying it. Your

effectPlayer

method is already doing something similar, but it's never called from anywhere.

 

The

int

argument of

Item#onUpdate

is the inventory slot containing the item, passing it to

EntityLivingBase#removePotionEffect

is a bad idea since it expects a completely different data type (a potion ID).

Could I possibly have an example please?

Regeneration is one of the potion effects that takes its duration remaining into account when applying its effect: it only heals on certain ticks.  Generally speaking, its every 10.  So setting the duration to 50 every tick, it ticks down to 49, 49 % 10 is not 0, no healing is applied.  Repeat.

Yeah but the problem is, the timer doesn't tick down at all?

Yeah but the problem is, the timer doesn't tick down at all?

 

Le me spell my post out a little more clearly:

 

Set the duration to 50

It ticks down to 49

49 % 10 is not 0, no healing is applied.

Set the duration to 50

It ticks down to 49

49 % 10 is not 0, no healing is applied.

Set the duration to 50

It ticks down to 49

49 % 10 is not 0, no healing is applied.

Set the duration to 50

It ticks down to 49

49 % 10 is not 0, no healing is applied.

Set the duration to 50

It ticks down to 49

49 % 10 is not 0, no healing is applied.

Set the duration to 50

It ticks down to 49

49 % 10 is not 0, no healing is applied.

 

Rinse, repeat.

Because you are adding a new potion effect every tick.

This new effect has the full duration.

 

Then how would I make it not add every tick and instead only at 0 seconds duration?