Wowza! Errors java.lang.NullPointerException

yahwho · Feb 1st 2018

Hi Guys,

I'm trying to write my first plugin, It's literally just a framework at the moment. I added my jar file to a created directory "plugins" in the server root and then typed in reloadplugins into the in-game console.

I got a message saying that it had failed (or something along those lines) and then on the server log I got tons of errors (as in repeatedly until I restarted the server).

Code

java.lang.NullPointerException
	at F.f.a(SourceFile:359)
	at F.f.messageReceived(SourceFile:118)
	at de.jiw.network.server.core.ServerUdpChannel.onMessageReceived(ServerUdpChannel.java:99)
	at de.jiw.network.server.core.AbstractServerChannel.dispatchUDP(AbstractServerChannel.java:71)
	at de.jiw.network.server.session.UdpSessionHandler.channelRead0(UdpSessionHandler.java:61)
	at de.jiw.network.server.session.UdpSessionHandler.channelRead0(UdpSessionHandler.java:16)
	at io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:105)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
	at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
	at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:102)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
	at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
	at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1359)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
	at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:935)
	at io.netty.channel.nio.AbstractNioMessageChannel$NioMessageUnsafe.read(AbstractNioMessageChannel.java:93)
	at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:645)
	at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:580)
	at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:497)
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:459)
	at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:858)
	at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:138)
	at java.lang.Thread.run(Unknown Source)

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From that can anyone see what I was doing wrong? I Appreciate you may need more info!

Minotorious · Feb 1st 2018

I can most likely help with your problem but I would need to see your "onMessageReceived" method and please also indicate which one line number 99 is

you could send me the whole code in pm if you wish

yahwho · Feb 1st 2018

Quote from Minotorious

code i

Hmm there isn't a line 99. Just 47 lines. I suspect it is the way I've compiled the package with the api

yahwho · Feb 1st 2018

The "plugin" is simply:

Code

package net.yahwho.medievalrealms;






import net.risingworld.api.Plugin;
import net.risingworld.api.events.EventMethod;
import net.risingworld.api.events.Listener;
import net.risingworld.api.events.player.PlayerCommandEvent;
import net.risingworld.api.events.player.PlayerConnectEvent;
import net.risingworld.api.objects.Player;






/**
 *
 * @version 1.0.0
 * @author yahwho
 */
public class MedievalRealms extends Plugin implements Listener {
    @Override
    public void onEnable() {
        System.out.println("Medieval Realms Plugin Starting. . . ");
    }






    @Override
    public void onDisable() {
        System.out.println("Stopping the Medieval Realms Plugin. . .");
    }
    @EventMethod
    public void onPlayerCommand(PlayerCommandEvent event) {
    }
  @EventMethod
  public void onPlayerConnectEvent(PlayerConnectEvent event)
  {
    Player player = event.getPlayer();
    String Playername = player.getName();
    //String group = player.getPermissionGroup();
    player.sendTextMessage(Playername + " welcome to Medieval Realms  1.0.0");
    if (player.isAdmin()) {
      player.sendTextMessage(Playername + " welcome to Medieval Realms  1.0.0");
    }
    }
}

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With of course the yml file

yahwho · Feb 1st 2018

Yeah looking inside my jar file I can also see the api jar files, which I'm sure is not right!

To get my code to compile (using NetBeans) I right clicked on my project name, selected properties, went to the libraries option and added the PluginAPI jar with the add JAR/folder option.

Which allow me to compile, as without it moans about the imports not working (i.e. net.risingworld.api.... )

To create my jar I right clicked on my project and selected "build"

It's been a while since I wrote any code, and I'm new to NetBeans (old Eclipse guy here).

This is my attempt at almost a "hello world" plugin.

Minotorious · Feb 1st 2018

oh what are you using to create the plugin? netbeans IDE?

yes your plugin code looks good so the error is somewhere in the compilation or the files you have included in the jar maybe

yahwho · Feb 1st 2018

I'm using NetBeans (I used to use Eclipse so NetBeans is all new to me)

The jar file does contain the api folders and classes too

I'll try to grab a screenshot or directory tree to illustrate

Minotorious · Feb 1st 2018

did you maybe put the api jar file in the src folder in your project?

yahwho · Feb 1st 2018

erm maybe

yahwho · Feb 1st 2018

could you tell me how the correct way to link the api jar to a project?

Minotorious · Feb 1st 2018

yeah that shouldn't be there, just put the api jar on your desktop or some random folder and then just include it as a library as you did before already.

see here: Getting started

yahwho · Feb 1st 2018

Brilliant, thanks Minotorious, I'll give that a shot. I was trying to be "organized" and keeping everything together.

I assume that by including the api in my source folder there was a conflict as to which class files to use, as in "my" copy of the api classes or the actual api classes on the server?

Edit: OK I've moved the api jar and recompiled, my new jar no longer contains the api classes

It's getting late so I will upload this and test it on the server tomorrow, and I'll post an update on how it goes.

Minotorious · Feb 1st 2018

perfect

yahwho · Feb 2nd 2018

Agh! Still no joy.

So here is my MedievalRealms plugin folder which contains my MedievalRealms.jar plugin file show in the following server tree.

Code

Folder PATH listing for volume Data
Volume serial number is 88C5-91B1
D:.
└───Rising World
    └───server_0.9.2.1
        ├───cache
        │   └───worlds
        │       └───Medieval Sandbox-1068054424
        ├───lib
        ├───Logs
        ├───permissions
        │   └───groups
        ├───permissions.example
        │   └───groups
        ├───plugins
        │   └───MedievalRealms
        ├───scripts
        │   └───AreaProtection
        │       ├───Groups
        │       └───listener
        └───Worlds
            └───Medieval Sandbox
                ├───customImages
                └───worldParts

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Here is my YML file called plugin.yml which lies in the resources folder within my packages src

Code

name: MedievalRealms
main: org.yahwho.medievalrealms.MedievalRealms
version: 1.0.0
author: Yahwho
team: Medieval Realms
description: "Medieval Realms Server Plugin"
license: MIT
website: https://medievalrealms.co.uk

Here is my java file

Code

package org.yahwho.medievalrealms;


import net.risingworld.api.Plugin;
import net.risingworld.api.events.EventMethod;
import net.risingworld.api.events.Listener;
import net.risingworld.api.events.player.PlayerCommandEvent;
import net.risingworld.api.events.player.PlayerConnectEvent;
import net.risingworld.api.objects.Player;
/**
 *
 * @version 1.0.0
 * @author yahwho
 */
public class MedievalRealms extends Plugin implements Listener {
    @Override
    public void onEnable() {
        System.out.println("Medieval Realms Plugin Starting. . . ");
        registerEventListener(this);
    }
    @Override
    public void onDisable() {
        System.out.println("Stopping the Medieval Realms Plugin. . .");
    }
    @EventMethod
    public void onPlayerCommand(PlayerCommandEvent event) {
    }
  @EventMethod
  public void onPlayerConnectEvent(PlayerConnectEvent event)
  {
    Player player = event.getPlayer();
    String Playername = player.getName();
    //String group = player.getPermissionGroup();
    player.sendTextMessage(Playername + " welcome to Medieval Realms  1.0.0");
    if (player.isAdmin()) {
      player.sendTextMessage(Playername + " welcome to Medieval Realms  1.0.0");
    }
    }
}

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I've also attached my compiled MedievalRealms.jar file.

On my desktop I've extracted my MedievalRealms.jar file alongside an extracted copy of ConnectToTS.jar

I've gone though all the files and structure and it look as far as I can tell identical?

But when I start my server with MedievalRealms.jar inside my servers root/plugins/MedievalRealms/ directory diddly squat happens?

If I type in reloadplugins in my in game console I get: WARNING: ERROR OCCURRED WHILST RELOADING THE PLUGINS!

Okay, so as a test, I removed my plugins folder and restarted server and typed in reloadplugins again, same thing happens WARNING: ERROR OCCURRED WHILST RELOADING THE PLUGINS! along with the (looping) error that I get in the log

Code

java.lang.NullPointerException
	at F.f.a(SourceFile:359)
	at F.f.messageReceived(SourceFile:118)
	at de.jiw.network.server.core.ServerUdpChannel.onMessageReceived(ServerUdpChannel.java:99)
	at de.jiw.network.server.core.AbstractServerChannel.dispatchUDP(AbstractServerChannel.java:71)
	at de.jiw.network.server.session.UdpSessionHandler.channelRead0(UdpSessionHandler.java:61)
	at de.jiw.network.server.session.UdpSessionHandler.channelRead0(UdpSessionHandler.java:16)
	at io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:105)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
	at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
	at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:102)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
	at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:340)
	at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1359)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:362)
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:348)
	at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:935)
	at io.netty.channel.nio.AbstractNioMessageChannel$NioMessageUnsafe.read(AbstractNioMessageChannel.java:93)
	at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:645)
	at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:580)
	at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:497)
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:459)
	at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:858)
	at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:138)
	at java.lang.Thread.run(Unknown Source)

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~~note: I have not tried installing any 3rd party plugin incl. the ConnectToTS.jar one~~

I'm trying this now - yep that doesn't do anything either entering /ts into chat comes up with "unknown command"

The file ConnectToTS.jar lies in this directory D:\Rising World\server_0.9.2.1\plugins\ConnetToTS\

yahwho · Feb 2nd 2018

I feel like the guy on the left

red51 · Feb 2nd 2018

Hmm... I tried the plugin, but I wasn't able to reproduce this error The plugin code looks fine btw. The error seems to be happening inside the game, although I'm not sure if it really causes this issue (or if this error just occurs because the plugin reload went wrong)... can you maybe post the whole server log here?

yahwho · Feb 2nd 2018

Thanks for the reply Red. Yes it's very strange. Tell you what, I will try rebooting the OS and trying again. I'll then provide the server log as well as any other info I think could be of any help.

yahwho · Feb 2nd 2018

Restart didn't help (worth a shot).

What I find odd is that I do not see something like:

Code

D:\Rising World\server_0.9.2.1\scripts

In the log, I expect I should see something like:

Code

D:\Rising World\server_0.9.2.1\plugins

somewhere.

red51 · Feb 2nd 2018

Thanks for the log! Apparently the plugin API does not get loaded properly. Is the setting plugins_enabled in the server.properties maybe set to false? It looks like this results in some errors once the "reloadplugins" command is used

yahwho · Feb 2nd 2018

Do you have a PayPal donate page anywhere Red? I'd like to buy you a beer!

Participate now!