[1.12.2]How to send command when player join a game?

[mlgmxyysd]

I use 

Minecraft.getMinecraft().player.sendChatMessage("/login " + password);

then game throw a NullPointerException.

Context:

package org.meowcat.autocommadner;
import net.minecraft.client.Minecraft;
import net.minecraftforge.common.MinecraftForge;
import net.minecraftforge.fml.common.FMLCommonHandler;
import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
import net.minecraftforge.fml.common.gameevent.PlayerEvent;
import net.minecraftforge.fml.relauncher.Side;
import net.minecraftforge.fml.relauncher.SideOnly;
import java.io.*;
import java.lang.reflect.Method;
import java.util.Properties;
public class JoinEvent {
	private Properties prop = new Properties();
	JoinEvent() {
		MinecraftForge.EVENT_BUS.register(this);
		FMLCommonHandler.instance().bus().register(this);
	}
	@SideOnly(Side.CLIENT)
	@SubscribeEvent
	public void PlayerJoinGame(PlayerEvent.PlayerLoggedInEvent event) throws IOException {
	    try{
	        Class mc = Class.forName(Minecraft.class.getName());
	        Method[] methods = mc.getMethods();
	        for (Method method : methods){
                Main.logger.info(method.getName());
            }
        } catch (ClassNotFoundException e ) {
            e.printStackTrace();
        }
		File file = new File("config/user.properties");
		if (!file.exists()) {
            Minecraft.getMinecraft().shutdown();
		}
        InputStream in = new BufferedInputStream(new FileInputStream("config/user.properties"));
        prop.load(in);
        String password = prop.getProperty("Password");
        String registered = prop.getProperty("IsRegistered");
        if (!registered.equals("true")) {
           Minecraft.getMinecraft().player.sendChatMessage("/register " + password + " " + password);
        } else {
           Minecraft.getMinecraft().player.sendChatMessage("/login " + password);
        }
	}
}

 

[Cadiboo]

What exactly are you trying to do? From an end-user persective

Edited December 27, 2018 by Cadiboo

[mlgmxyysd]

Auto send a command when player join game (server/single).

[diesieben07]

Why are you making register / login commands? Mojang already has accounts, there is no need to make a secondary account system.

[mlgmxyysd]

24 minutes ago, diesieben07 said:

Why are you making register / login commands? Mojang already has accounts, there is no need to make a secondary account system.

That is not main issue.

I can replace by any command,it only is a placeholder.

[diesieben07]

It might not be. Still, why? This usually means you are pirating the game.

 

You need to use ClientTickEvent, PlayedLoggedInEvent is server-side only. And that is not how @SideOnly works.

[mlgmxyysd]

9 hours ago, diesieben07 said:

It might not be. Still, why? This usually means you are pirating the game.

 

You need to use ClientTickEvent, PlayedLoggedInEvent is server-side only. And that is not how @SideOnly works.

The mod is a client mod,not a server mod.

[mlgmxyysd]

9 hours ago, diesieben07 said:

It might not be. Still, why? This usually means you are pirating the game.

 

You need to use ClientTickEvent, PlayedLoggedInEvent is server-side only. And that is not how @SideOnly works.

No,I bought Minecraft.

[diesieben07]

1 hour ago, mlgmxyysd said:

The mod is a client mod,not a server mod.

Yes, that is why you need ClientTickEvent.

[mlgmxyysd]

3 hours ago, diesieben07 said:

Yes, that is why you need ClientTickEvent.

It not work.

When game inited(not join a game),force close by NullPointer.

[Cadiboo]

send your code and the error

[mlgmxyysd]

19 hours ago, Cadiboo said:

send your code and the error

All code and error is posted at top.

[diesieben07]

11 hours ago, mlgmxyysd said:

All code and error is posted at top.

The code above has not changed. No error was posted.

[mlgmxyysd]

13 hours ago, diesieben07 said:

The code above has not changed. No error was posted.

It may cause by network problem.

package org.meowcat.autocommadner;
import net.minecraft.client.Minecraft;
import net.minecraftforge.common.MinecraftForge;
import net.minecraftforge.fml.common.FMLCommonHandler;
import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
import net.minecraftforge.fml.common.gameevent.TickEvent;
import net.minecraftforge.fml.relauncher.Side;
import net.minecraftforge.fml.relauncher.SideOnly;
import java.io.*;
import java.lang.reflect.Method;
import java.util.Properties;
public class JoinEvent {
	private Properties prop = new Properties();
	JoinEvent() {
		MinecraftForge.EVENT_BUS.register(this);
		FMLCommonHandler.instance().bus().register(this);
	}
	@SideOnly(Side.CLIENT)
	@SubscribeEvent
	public void PlayerJoinGame(TickEvent.ClientTickEvent event) throws IOException {
	    try{
	        Class mc = Class.forName(Minecraft.class.getName());
	        Method[] methods = mc.getMethods();
	        for (Method method : methods){
                Main.logger.info(method.getName());
            }
        } catch (ClassNotFoundException e ) {
            e.printStackTrace();
        }
		File file = new File("config/user.properties");
		if (!file.exists()) {
            Minecraft.getMinecraft().shutdown();
		}
        InputStream in = new BufferedInputStream(new FileInputStream("config/user.properties"));
        prop.load(in);
        String password = prop.getProperty("Password");
        String registered = prop.getProperty("IsRegistered");
        if (!registered.equals("true")) {
           Minecraft.getMinecraft().player.sendChatMessage("/register " + password + " " + password);
        } else {
           Minecraft.getMinecraft().player.sendChatMessage("/login " + password);
        }
	}
}

java.lang.NullPointerException: Unexpected error
	at org.meowcat.autocommadner.JoinEvent.PlayerJoinGame(JoinEvent.java:42)
	at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_18_JoinEvent_PlayerJoinGame_ClientTickEvent.invoke(.dynamic)
	at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90)
	at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:182)
	at net.minecraftforge.fml.common.FMLCommonHandler.onPreClientTick(FMLCommonHandler.java:344)
	at net.minecraft.client.Minecraft.func_71407_l(Minecraft.java:1708)
	at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:1098)
	at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:398)
	at net.minecraft.client.main.Main.main(SourceFile:123)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
	at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

These are codes & errors

[Cadiboo]

What are you trying to do with that code?

Edited December 30, 2018 by Cadiboo

[diesieben07]

16 hours ago, mlgmxyysd said:

try{ Class mc = Class.forName(Minecraft.class.getName()); Method[] methods = mc.getMethods(); for (Method method : methods){ Main.logger.info(method.getName()); } } catch (ClassNotFoundException e ) { e.printStackTrace(); }

Why on earth is this here? And blindly catching ClassNotFoundException and ignoring it is a bad idea. Handle exceptions properly.

 

16 hours ago, mlgmxyysd said:

File file = new File("config/user.properties"); if (!file.exists()) { Minecraft.getMinecraft().shutdown(); } InputStream in = new BufferedInputStream(new FileInputStream("config/user.properties")); prop.load(in); String password = prop.getProperty("Password"); String registered = prop.getProperty("IsRegistered");

Why on earth are you doing this every tick?! And registered should not be an option. Do not pirate the game.

 

16 hours ago, mlgmxyysd said:

Minecraft.getMinecraft().player.sendChatMessage("/register " + password + " " + password);

You can only do this when the game is actually connected to a server. ClientTickEvent fires every client tick (duh), which is also during e.g. the main menu.

[mlgmxyysd]

5 hours ago, diesieben07 said:

Why on earth is this here? And blindly catching ClassNotFoundException and ignoring it is a bad idea. Handle exceptions properly.

 

Why on earth are you doing this every tick?! And registered should not be an option. Do not pirate the game.

 

You can only do this when the game is actually connected to a server. ClientTickEvent fires every client tick (duh), which is also during e.g. the main menu.

Please don't get caught up in the secondary problem.

I only want to solve NullPointerException.

[mlgmxyysd]

11 hours ago, Cadiboo said:

What are you trying to do with that code?

When player join a game (server/single), player will send a message(or command) automatically.

[diesieben07]

20 minutes ago, mlgmxyysd said:

Please don't get caught up in the secondary problem.

Pirating the game is not a secondary problem.

Please clearly state why that isRegistered option is present. If not I will assume it is for enabling pirated "accounts", in which case you will receive a ban.

[mlgmxyysd]

3 minutes ago, diesieben07 said:

Pirating the game is not a secondary problem.

Please clearly state why that isRegistered option is present. If not I will assume it is for enabling pirated "accounts", in which case you will receive a ban.

A bukkit plugin named Authme.

[hiotewdew]

On 12/27/2018 at 10:51 AM, diesieben07 said:

It might not be. Still, why? This usually means you are pirating the game.

 

You need to use ClientTickEvent, PlayedLoggedInEvent is server-side only. And that is not how @SideOnly works.

Not to go too off topic, but /login can be used on servers as a staff security measure as well as for cracked server auth. So, it's not always malicious. I once had to use it on my online mode server because we had this hacker who somehow figured out that commands could be run by staff before they were authenticated (I have no idea how, but I'm not lying, he'd done it) and so I had to add a login command for staff to counteract it.

[diesieben07]

8 hours ago, hiotewdew said:

Not to go too off topic, but /login can be used on servers as a staff security measure as well as for cracked server auth. So, it's not always malicious. I once had to use it on my online mode server because we had this hacker who somehow figured out that commands could be run by staff before they were authenticated (I have no idea how, but I'm not lying, he'd done it) and so I had to add a login command for staff to counteract it.

I know, and this is the only reason this thread is not locked yet.

 

13 hours ago, mlgmxyysd said:

A bukkit plugin named Authme.

This explains nothing.

 

As far as the cause of your exception goes, I have already explained that above.

[mlgmxyysd]

On 12/31/2018 at 11:20 PM, diesieben07 said:

I know, and this is the only reason this thread is not locked yet.

 

This explains nothing.

 

As far as the cause of your exception goes, I have already explained that above.

OKAY, I does not use /login command, replace /login to /exp ok?

IS THIS OK?

package org.meowcat.autocommadner;
import net.minecraft.client.Minecraft;
import net.minecraftforge.common.MinecraftForge;
import net.minecraftforge.fml.common.FMLCommonHandler;
import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
import net.minecraftforge.fml.common.gameevent.TickEvent;
import net.minecraftforge.fml.relauncher.Side;
import net.minecraftforge.fml.relauncher.SideOnly;
import java.io.*;
import java.lang.reflect.Method;
import java.util.Properties;
public class JoinEvent {
	private Properties prop = new Properties();
	JoinEvent() {
		MinecraftForge.EVENT_BUS.register(this);
		FMLCommonHandler.instance().bus().register(this);
	}
	@SideOnly(Side.CLIENT)
	@SubscribeEvent
	public void PlayerJoinGame(TickEvent.ClientTickEvent event) throws IOException {
	    try{
	        Class mc = Class.forName(Minecraft.class.getName());
	        Method[] methods = mc.getMethods();
	        for (Method method : methods){
                Main.logger.info(method.getName());
            }
        } catch (ClassNotFoundException e ) {
            e.printStackTrace();
        }
            Minecraft.getMinecraft().player.sendChatMessage("/exp");
	}
}

[mlgmxyysd]

On 12/31/2018 at 11:20 PM, diesieben07 said:

As far as the cause of your exception goes, I have already explained that above.

And 

ClientTickEvent, PlayedLoggedInEvent

dont have sendChatMessage() method.

[mlgmxyysd]

On 12/31/2018 at 2:24 PM, hiotewdew said:

Not to go too off topic, but /login can be used on servers as a staff security measure as well as for cracked server auth. So, it's not always malicious. I once had to use it on my online mode server because we had this hacker who somehow figured out that commands could be run by staff before they were authenticated (I have no idea how, but I'm not lying, he'd done it) and so I had to add a login command for staff to counteract it.

Yes, it is necessary to use unofficial login system in offline-mode server.