write

public static boolean check(ArrayList<ItemStack> mutantzombie_4l,  ItemStack meep)
{
    for(int i = 0; i < mutantzombie_4l.size(); i++)
    {
        if(ItemStack.areItemStacksEqual(mutantzombie_41.get(i), meep))
        {
            return true;
        }
    }
    return false;
}