public void checkTorch() {
        if (world.isAirBlock((int) player.posX, (int) player.posY, (int) player.posZ)) { //Checks if the block your'e trying to place a torch in isn't air. You can change it to the block you want.
            for (int i = 0; i < player.inventory.getSizeInventory(); i++) { //Checks in the entire player's inventory. If you want to just check the hotbar, use 8 instead of the inventory size, since the hotbar is slots 0-8.
                ItemStack stack = player.inventory.getStackInSlot(i);
                if (stack.isItemEqual(new ItemStack(Blocks.torch))) { //Checks if the item is a torch.
                    stack.stackSize--;
                    world.setBlock((int) player.posX, (int) player.posY, (int) player.posZ, Blocks.torch);
                    return; //Breaks if it has already placed a torch - no sense to keep looking for a torch.
                }
            }
        }
    }