I have programmed my mod, so it will send a packet:

public class SlotChangeMessage implements IMessage{

int x,y,z;

public SlotChangeMessage(int x, int y, int z){
	this.x = x;
	this.y = y;
	this.z = z;
}

@Override
public void fromBytes(ByteBuf buf) {
	this.x = buf.readInt();
	this.y = buf.readInt();
	this.z = buf.readInt();
}

@Override
public void toBytes(ByteBuf buf) {
	buf.writeInt(x);
	buf.writeInt(y);
	buf.writeInt(z);
}

public static class Handler implements IMessageHandler<SlotChangeMessage, SlotChangeMessage>{

	@Override
	public SlotChangeMessage onMessage(SlotChangeMessage message, MessageContext ctx) {
		World world = ctx.getServerHandler().playerEntity.worldObj;
		TileEntityTableLives tile = (TileEntityTableLives) world.getTileEntity(message.x, message.y, message.z);
		if(tile.getStackInSlot(0) == new ItemStack(Items.diamond)){
			tile.setInventorySlotContents(0, new ItemStack(ModItems.crystalVivium));
		}
		return null;
	}	
}
}

 

but it crashes!

 

I have heared, that the constructor must be empty, but how do i then put the values into the packet?

Your message can have multiple constructors, as long as one of them takes no arguments.

Thanks, Its not crashing anymore, but it still doesnt do anything, i added a println statement, to check if the values are sent properly, and its recieving the values.

Thanks, Its not crashing anymore, but it still doesnt do anything, i added a println statement, to check if the values are sent properly, and its recieving the values.

 

Is your handler being called? Is the handler calling

setInventorySlotContents

?

Im not calling the handler, all im doing, is this :

MainRegistry.network.sendToServer(new SlotChangeMessage(tile));

Where do i call the handler?

You don't call the handler yourself, FML should be calling it when the message is received on the server.

 

Have you registered your message and handler using

SimpleNetworkWrapper#registerMessage

?

It is registered in the pre-init method.

Is there a way to send the tileentity, istead of getting it by coordinates?

No, you need to send the coordinates so you can modify the

TileEntity

that already exists there.

 

Is your handler being called? Is the handler calling

setInventorySlotContents

?

if(tile.getStackInSlot(0) == new ItemStack(Items.diamond)){
tile.setInventorySlotContents(0, new ItemStack(ModItems.crystalVivium));
}

it is

I can see that you're calling

setInventorySlotContents

, but is the

if

condition actually met at the time the packet is received? Is the handler being called?

 

Set a breakpoint in

Handler#onMessage

, run Minecraft in debug mode and step through the code.

It was the condition, without it, it works!

It seems, that getting the itemstack, returns "null".

I got it, the ItemStack array sots, wasn't set to be public!

Thank You SO much for helping