I do code .addExperienceLevel(int); By GuiScreen.

 

@Override
protected void actionPerformed(GuiButton button){
	switch(button.id){
	case 1:
		EntityPlayer player = Minecraft.getMinecraft().thePlayer;

		int xp = player.experienceLevel;
		player.addExperienceLevel(-1000);
	}

 

If LV 1100 it will remaining 100 but if earn xp 1 it retrun 100 to 1100.

GUIs are client-only, but the server is in control of the game. If you make changes on the client, they'll just be overwritten by the server's values.

 

You need to send a packet to the server telling it that the player pressed the button so it can take the appropriate action. diesieben07 has a tutorial on the Simple Network Wrapper here.

In the absence of message I have to do ?

What do you mean?

 

If your mod isn't on the server, you can't modify server-controlled values like experience unless you can use a vanilla packet to do it for you. There's no packet that modifies experience. You could send a chat packet to execute the

/xp

command, but that would only work if the player has permission to use it.

I mean want will make guiscreen give xp by not command.

but you tell me. give me send packate.

 

If use Guiscreen for send packate. I will can do it ?

 

If can do it. How to can do ?

Use the Simple Network Wrapper to send packets between the client and server. Look at the tutorial I linked in my first post for an explanation of how to use the system.

The Simple is registerMessage()

 

network = NetworkRegistry.INSTANCE.newSimpleChannel("MyChannel");
       network.registerMessage(MyMessage.Handler.class, MyMessage.class, 0, Side.SERVER);

 

I want use void in NetworkRegistry ?

That registration code looks correct, but I can't understand what you're asking.

I can't understand at this code

 

network = NetworkRegistry.INSTANCE.newSimpleChannel("MyChannel");
network.registerMessage(MyMessage.Handler.class, MyMessage.class, 0, Side.SERVER);

 

I want use network. ? of guiscreen

registerMessage can use with GuiScreen ?

what at can use with GuiScreen ? for send packets between the client and server.

MainMod.networkHandler.sendAFuckingPacket()

you mean networkHandler = NetworkRegistry.INSTANCE.newSimpleChannel("MyChannel");

and use networkHandler.sendAFuckingPacket ?

It isn't literally called "sendAFuckingPacket" but yes.