Minecraft Forums

I am a beginner to develop a minecraft mode in 1.11.2.

I tested this code on server connection status(bukkit server)

#1
Minecraft.getMinecraft().getIntegratedServer();
// return null

#2
FMLCommonHandler.instance().getMinecraftServerInstance();
// return null

#3
WorldServer worldServer = DimensionManager.getWorld(0); // default world
GameProfile gameProfile = new GameProfile(UUID.randomUUID(), "FakePlayer");
//worldServer is null
FakePlayer fakePlayer = new FakePlayer(worldServer, gameProfile);
//NullPointerException
MinecraftServer minecraftServer = fakePlayer.mcServer;

why this codes return null?

which method should I use?

lol you used my stackoverflow answer.

The first one, is retrieving the integrated server; which is the one that runs on the client for singleplayer worlds. A bukkit server doesn't have a integrated server, since it's a dedicated server and is not on the client.

The second one, needs more elaboration. It could be that you are getting the server instance before it's initialization.

The third one, is probably the second one.

Where are you trying to get the server instance? What are you trying to do with it?

I getting server instance in KeyInput Listener and want get NetHandlerPlayServer instance
like this

NetHandlerPlayServer playServer = new NetHandlerPlayServer(minecraftServer, FMLCommonHandler.instance().getClientToServerNetworkManager(), playerMp);
//param is MinecraftServer, NetworkManager, EntityPlayerMP

but all of getting MinecraftServer instance method return null..

I want to know the right way.

You can't access the server instance from the logical client, that would be reaching across sides.

It's possible to do this in single player or as the LAN host, but you'll almost certainly break things if you do. In multiplayer, the logical client and logical server are running on two completely different machines.

You can read more on sides here.

If you want to communicate between the logical client and logical server, you need to use packets.

What are you actually trying to do?

My original plan is placing block mid-air(bottom of player) using player interact logic.

first i want test that placing block bottom of player.

@SubscribeEvent
public void onKeyInput(InputEvent.KeyInputEvent event) {
 if (this.options.isPressed()) {
 Minecraft minecraft = Minecraft.getMinecraft();
 EntityPlayerSP player = minecraft.player;
 BlockPos pos = new BlockPos(player.posX, player.posY - 1, player.posZ);
 minecraft.playerController.processRightClickBlock(player, minecraft.world, pos, EnumFacing.DOWN, new Vec3d(0.5, 0.5, 0.5), EnumHand.MAIN_HAND);
 //not work in server

 CPacketPlayerTryUseItemOnBlock packet = new CPacketPlayerTryUseItemOnBlock(pos, EnumFacing.DOWN, EnumHand.MAIN_HAND, 0, 0, 0);
 player.connection.sendPacket(packet);
 //not work in server

 NetHandlerPlayServer playServer = new NetHandlerPlayServer(minecraftServer, networkManager, player);
 //i can't access minecraftServer instance
 playServer.processTryUseItemOnBlock(packet);
 }
}

You should be handling your keybindings in ClientTickEvent instead of InputEvent.KeyInputEvent. Make sure that TickEvent#phase is TickEvent.Phase.END. diesieben07 explains this here.

Calling PlayerControllerMP#processRightClickBlock on Minecraft#playerController on the client side should work on both the integrated and dedicated servers, though you should pass it EnumFacing.UP instead of DOWN as that's the face that the player would have clicked on to place the block below them.

You should never need to create your own instance of NetHandlerPlayServer. You should never use classes that belong to the logical server (e.g. NetHandlerPlayServer) from the logical client or vice versa, this is reaching across sides.

You can see a working example of a keybinding that tries to place the player's held block below them here.

Test Result

(tested in bukkit server)

Thanks for your code
but github code not work for me...
placed block change to air and consumed item stack is restored when slot clicked.

I've created a client-only mod with the key binding and it worked on both a Forge and Vanilla server. If it's not working on Bukkit, that's an issue with Bukkit and one I can't help you with.