I have register my client command, its work properly in Singleplayer but on the server it throwing an NullPointerException.

 

 

[19:10:18] [Client thread/INFO]: [CHAT] An unknown error occurred while attempting to perform this command

[19:10:18] [Client thread/WARN]: Couldn't process command: 'getplayerpos Slender666'

java.lang.NullPointerException

at stevekung.mods.indicatorutils.util.CommandGetPlayerPosition.execute(CommandGetPlayerPosition.java:52) ~[CommandGetPlayerPosition.class:?]

at net.minecraft.command.CommandHandler.tryExecute(CommandHandler.java:109) [CommandHandler.class:?]

at net.minecraftforge.client.ClientCommandHandler.executeCommand(ClientCommandHandler.java:97) [ClientCommandHandler.class:?]

at net.minecraft.client.gui.GuiScreen.sendChatMessage(GuiScreen.java:478) [GuiScreen.class:?]

at net.minecraft.client.gui.GuiScreen.sendChatMessage(GuiScreen.java:469) [GuiScreen.class:?]

at net.minecraft.client.gui.GuiChat.keyTyped(GuiChat.java:129) [GuiChat.class:?]

at net.minecraft.client.gui.GuiScreen.handleKeyboardInput(GuiScreen.java:645) [GuiScreen.class:?]

at net.minecraft.client.gui.GuiScreen.handleInput(GuiScreen.java:593) [GuiScreen.class:?]

at net.minecraft.client.Minecraft.runTick(Minecraft.java:1797) [Minecraft.class:?]

at net.minecraft.client.Minecraft.runGameLoop(Minecraft.java:1118) [Minecraft.class:?]

at net.minecraft.client.Minecraft.run(Minecraft.java:406) [Minecraft.class:?]

at net.minecraft.client.main.Main.main(Main.java:118) [Main.class:?]

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_101]

at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_101]

at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_101]

at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_101]

at net.minecraft.launchwrapper.Launch.launch(Launch.java:135) [launchwrapper-1.12.jar:?]

at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.12.jar:?]

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_101]

at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_101]

at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_101]

at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_101]

at net.minecraftforge.gradle.GradleStartCommon.launch(GradleStartCommon.java:97) [start/:?]

at GradleStart.main(GradleStart.java:26) [start/:?]

 

 

My Command

 

 

package stevekung.mods.indicatorutils.util;

 

import java.util.Collections;

import java.util.List;

 

import javax.annotation.Nullable;

 

import net.minecraft.client.Minecraft;

import net.minecraft.client.resources.I18n;

import net.minecraft.command.CommandBase;

import net.minecraft.command.CommandException;

import net.minecraft.command.ICommandSender;

import net.minecraft.command.WrongUsageException;

import net.minecraft.entity.Entity;

import net.minecraft.entity.player.EntityPlayer;

import net.minecraft.entity.player.EntityPlayerMP;

import net.minecraft.server.MinecraftServer;

import net.minecraft.util.math.BlockPos;

import net.minecraft.util.math.MathHelper;

import net.minecraft.util.text.TextComponentTranslation;

 

public class CommandGetPlayerPosition extends CommandBase

{

    @Override

    public int getRequiredPermissionLevel()

    {

        return 0;

    }

 

    @Override

    public String getCommandUsage(ICommandSender sender)

    {

        return "/" + this.getCommandName();

    }

 

    @Override

    public String getCommandName()

    {

        return "getplayerpos";

    }

 

    @Override

    public void execute(MinecraftServer server, ICommandSender sender, String[] args) throws CommandException

    {

        if (args.length < 1)

        {

            throw new WrongUsageException("commands.getplayerpos.fail", new Object[] { this.getCommandUsage(sender) });

        }

        else

        {

            Entity player = this.getPlayerByUsername(args[0]);

            System.out.println(I18n.format("%s %s %s %s", new Object[] { Integer.valueOf(MathHelper.floor_double(player.posX)), Integer.valueOf(MathHelper.floor_double(player.posY)), Integer.valueOf(MathHelper.floor_double(player.posZ)), player.worldObj.provider.getDimensionType().getName() }));

            Minecraft.getMinecraft().thePlayer.addChatMessage(new TextComponentTranslation("commands.getplayerpos.success", new Object[] { player.getName(), Integer.valueOf(MathHelper.floor_double(player.posX)), Integer.valueOf(MathHelper.floor_double(player.posY)), Integer.valueOf(MathHelper.floor_double(player.posZ)), player.worldObj.provider.getDimensionType().getName() }));

        }

    }

 

    @Override

    public List<String> getTabCompletionOptions(MinecraftServer server, ICommandSender sender, String[] args, @Nullable BlockPos pos)

    {

        return Collections.<String>emptyList();

    }

 

    public EntityPlayer getPlayerByUsername(String username)

    {

        EntityPlayer player = Minecraft.getMinecraft().thePlayer;

 

        if (player.getName().equalsIgnoreCase(username))

        {

            return player;

        }

        return null;

    }

 

    @Override

    public boolean isUsernameIndex(String[] args, int index)

    {

        return index == 0;

    }

}

 

 

EventHandler

 

 

    @EventHandler

    public void init(FMLInitializationEvent event)

    {

        MinecraftForge.EVENT_BUS.register(new IndicatorUtilsEventHandler());

        MinecraftForge.EVENT_BUS.register(this);

 

        if (event.getSide() == Side.CLIENT)

        {

            ClientCommandHandler.instance.registerCommand(new CommandGetPlayerPosition());

        }

    }

 

 

My main problem is I can't get other player name in the server except myself.

My main problem is I can't get other player name in the server except myself.

Well, of course you cannot, the client only knows about itself.

You would have to learn about packets and request the player's position from the server.

The error is you check if the client players name is the same as the passed name, if not you return null. You then try to do something with that null variable. As Matryoshika said the server knows where the players are, while the client does not.

Also I can't use my own packet if my mod isn't on the server. Only use in Realm Server.

 

clientSideOnly = true

 

There is the way to get player position in the server?