Method hasEffect

src/main/java/net/minecraft/item/ItemPotion.java:333–337

(ItemStack stack)

    }

    public boolean hasEffect(ItemStack stack)
    {
        List<PotionEffect> list = this.getEffects(stack);
        return list != null && !list.isEmpty();
    }

    /**
     * returns a list of items with the same ID, but different meta (eg: dye returns 16 items)