Hello,

I've made an item that is drunken to heal the player, and when it is drunk it reduces the uses by one. However, when I drink it in survival, a weird bug occurs:

A red -1 appears on the icon, which briefly changes to a -3. When I hit something with it, it'll be instantly destroyed.

What have I done wrong?

[spoiler=Images]

 

[spoiler=Item Code]

package com.t10a.crystalflask.items;

import com.t10a.crystalflask.CrystalFlask;
import com.t10a.crystalflask.Reference;
import com.t10a.crystalflask.init.ModItems;
import net.minecraft.entity.EntityLivingBase;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.init.MobEffects;
import net.minecraft.item.EnumAction;
import net.minecraft.item.Item;
import net.minecraft.item.ItemStack;
import net.minecraft.potion.PotionEffect;
import net.minecraft.util.ActionResult;
import net.minecraft.util.EnumActionResult;
import net.minecraft.util.EnumHand;
import net.minecraft.world.World;

import javax.annotation.Nullable;
import java.util.List;

public class ItemCrystalFlask extends Item
{
    public int uses;
    public ItemCrystalFlask()
    {
        setUnlocalizedName(Reference.MOD_ID + "." + Reference.ItemBase.ESTUS.getUnlocalizedName());
        setRegistryName(Reference.ItemBase.ESTUS.getRegistryName());
        setCreativeTab(CrystalFlask.ESTUSTAB);
        this.setMaxStackSize(1);
        this.uses = 5;
        this.setMaxDamage(uses);
    }

    @Override
    public void addInformation(ItemStack stack, EntityPlayer player, List<String> list, boolean par4)
    {
        list.add("A crystallised flask, containing a magical flame. Drink to restore HP.");
        list.add("(totally not an estus flask)");
    }

    public int getMaxItemUseDuration(ItemStack stack)
    {
        return 32;
    }

    public EnumAction getItemUseAction(ItemStack stack)
    {
        return EnumAction.DRINK;
    }

    public ActionResult<ItemStack> onItemRightClick(ItemStack itemStackIn, World worldIn, EntityPlayer playerIn, EnumHand hand)
    {
        playerIn.setActiveHand(hand);
        return new ActionResult(EnumActionResult.SUCCESS, itemStackIn);
    }

    @Nullable
    public ItemStack onItemUseFinish(ItemStack stack, World worldIn, EntityLivingBase entityLiving)
    {
        if (entityLiving instanceof EntityPlayer && !((EntityPlayer)entityLiving).capabilities.isCreativeMode)
        {
            --stack.stackSize;
        }

        if (!worldIn.isRemote)
        {
            entityLiving.addPotionEffect(new PotionEffect(MobEffects.INSTANT_HEALTH));
            stack.damageItem(1, entityLiving);
        }

        if (entityLiving instanceof EntityPlayer && !((EntityPlayer)entityLiving).capabilities.isCreativeMode)
        {
            --stack.stackSize;
        }

        return super.onItemUseFinish(stack, worldIn, entityLiving);
    }
}

 

You subtract from the stacksize then you damage the item?

Whoops, didn't see that. However, after fixing it and adding a tidbit of code that tells the game if it's empty or not, it'll just ignore it and allow the usage when (nearly) empty anyway.

 

package com.t10a.crystalflask.items;

import com.t10a.crystalflask.CrystalFlask;
import com.t10a.crystalflask.Reference;
import net.minecraft.entity.EntityLivingBase;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.init.MobEffects;
import net.minecraft.item.EnumAction;
import net.minecraft.item.Item;
import net.minecraft.item.ItemStack;
import net.minecraft.potion.PotionEffect;
import net.minecraft.util.ActionResult;
import net.minecraft.util.EnumActionResult;
import net.minecraft.util.EnumHand;
import net.minecraft.world.World;

import javax.annotation.Nullable;
import java.util.List;

public class ItemCrystalFlask extends Item
{
    public int uses;
    public ItemCrystalFlask()
    {
        setUnlocalizedName(Reference.MOD_ID + "." + Reference.ItemBase.ESTUS.getUnlocalizedName());
        setRegistryName(Reference.ItemBase.ESTUS.getRegistryName());
        setCreativeTab(CrystalFlask.ESTUSTAB);
        this.setMaxStackSize(1);
        this.uses = 5;
        this.setMaxDamage(uses);
    }

    public boolean getIsEmpty()
    {
        if (this.getMaxDamage() == 1)
            return true;
        else
            return false;
    }

    @Override
    public void addInformation(ItemStack stack, EntityPlayer player, List<String> list, boolean par4)
    {
        list.add("A crystallised flask, containing a magical flame. Drink to restore HP.");
        list.add("(totally not an estus flask)");
    }

    public int getMaxItemUseDuration(ItemStack stack)
    {
        return 32;
    }

    public EnumAction getItemUseAction(ItemStack stack)
    {
        if (getIsEmpty())
            return EnumAction.NONE;
        else return EnumAction.DRINK;
    }

    public ActionResult<ItemStack> onItemRightClick(ItemStack itemStackIn, World worldIn, EntityPlayer playerIn, EnumHand hand)
    {
        playerIn.setActiveHand(hand);
        return new ActionResult(EnumActionResult.SUCCESS, itemStackIn);
    }

    @Nullable
    public ItemStack onItemUseFinish(ItemStack stack, World worldIn, EntityLivingBase entityLiving)
    {
        if (!worldIn.isRemote)
        {
            entityLiving.addPotionEffect(new PotionEffect(MobEffects.INSTANT_HEALTH));

        }

        if (entityLiving instanceof EntityPlayer && !((EntityPlayer)entityLiving).capabilities.isCreativeMode)
        {
            stack.damageItem(1, entityLiving);
        }

        return super.onItemUseFinish(stack, worldIn, entityLiving);
    }
}