Forge Modding Tutorial 12

//TileEntitycode:

    public void onDataPacket(NetworkManager net, S35PacketUpdateTileEntity pkt) {
        NBTTagCompound tag = pkt.getNbtCompound();
        this.readFromNBT(tag);
    }

    public Packet getDescriptionPacket() {
        NBTTagCompound tag = new NBTTagCompound();
        writeToNBT(tag);
        return new S35PacketUpdateTileEntity(getPos(), 1, tag);
    }

//Block Code:
    @Override
    public boolean onBlockActivated(World worldIn, BlockPos pos, IBlockState state, EntityPlayer playerIn,
            EnumFacing side, float hitX, float hitY, float hitZ) {
        TutorialTileEntity tile = (TutorialTileEntity)worldIn.getTileEntity(pos);
        if (playerIn.inventory.getCurrentItem() != null
                && playerIn.inventory.getCurrentItem().getItem() instanceof ItemAlienWand) {

             tile.isActive = !tile.isActive;
            if (worldIn.isRemote) {

                 playerIn.addChatComponentMessage(
                 new ChatComponentText(
                 "Die maschiene ist "
                 + (tile.isActive ? EnumChatFormatting.GREEN + "aktiviert"
                 : EnumChatFormatting.RED + "ausser Betrieb")
                 + EnumChatFormatting.RESET + "."));
            }
        } else {

            playerIn.addChatComponentMessage(
                    new ChatComponentText(EnumChatFormatting.BLUE + "Hier kann ganz viel passieren!"));
        }
        return super.onBlockActivated(worldIn, pos, state, playerIn, side, hitX, hitY, hitZ);
    }