Must be a simple way sure ItemStack item=""""Any item stack of any inventory""" if(item.getType()==Material.WHITE_SHULKER_BOX || item.getType()==Material.RED_SHULKER_BOX || item.getType()==Material.GREEN_SHULKER_BOX || ... )
I believe you can get all shulker boxes by the shulker box tag. Code:java Set<Material> shulkerBoxes = Tag.SHULKER_BOXES.getValues();