Solved NullPointerException error

Discussion in 'Plugin Development' started by KarimAKL, May 3, 2018.

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  1. Offline

    KarimAKL

    I've got this error when i send messages from my messages.yml file. :/ Here is the code that gets the NullPointerException error:
    Code:Java
    1.  
    2. p.sendMessage(ChatColorUtil.chat(plugin.messages.getString("message").replace("{world}", world)));
    3.  

    And here is the "message" in the messages.yml file:
    Code:
    message: "&aYou are currently in world {world}"
    I think the problem is how i create the message.yml file in my main class, this is how i do it:
    Code:Java
    1.  
    2. public File messagesFile = new File(this.getDataFolder() + "messages.yml");
    3. public FileConfiguration messages = YamlConfiguration.loadConfiguration(messagesFile);
    4.  
    5. @Override
    6.     public void onEnable() {
    7.         if (!getDataFolder().exists()) {
    8.             getDataFolder().mkdirs();
    9.             if (!messagesFile.exists()) {
    10.                 this.saveResource("messages.yml", false);
    11.             }
    12.         } else {
    13.             if (!messagesFile.exists()) {
    14.                 this.saveResource("messages.yml", false);
    15.             }
    16.  

    And here is the error when i try executing the command:
    Code:
    [09:04:53 INFO]: Karim09 issued server command: /world
[09:04:53 ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'world' in plugin WorldTeller v1.0
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46) ~[spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:141) ~[spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at org.bukkit.craftbukkit.v1_8_R3.CraftServer.dispatchCommand(CraftServer.java:641) ~[spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at net.minecraft.server.v1_8_R3.PlayerConnection.handleCommand(PlayerConnection.java:1162) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at net.minecraft.server.v1_8_R3.PlayerConnection.a(PlayerConnection.java:997) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at net.minecraft.server.v1_8_R3.PacketPlayInChat.a(PacketPlayInChat.java:45) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at net.minecraft.server.v1_8_R3.PacketPlayInChat.a(PacketPlayInChat.java:1) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at net.minecraft.server.v1_8_R3.PlayerConnectionUtils$1.run(SourceFile:13) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.8.0_161]
        at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.8.0_161]
        at net.minecraft.server.v1_8_R3.SystemUtils.a(SourceFile:44) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:715) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:374) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:654) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:557) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_161]
Caused by: java.lang.NullPointerException
        at me.karim.worldteller.commands.CommandWorld.onCommand(CommandWorld.java:62) ~[?:?]
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) ~[spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        ... 15 more
    I have tried changing the line which causes the error to something like this:
    Code:Java
    1.  
    2. p.sendMessage("Does this work?");
    3.  

    And then it didn't cause any errors. :7 Btw the "ChatColorUtil.chat" is just a static for ChatColor.translateAlternateColorCodes :p
     
    KarimAKL, May 3, 2018
    #1
  2. Online

    timtower Administrator Administrator Moderator

    @KarimAKL Please post the involved classes in full.
    My first guess is that plugin is null.
     
    timtower, May 3, 2018
    #2
  3. Offline

    KarimAKL

    @timtower What do you mean "plugin is null"?
     
    KarimAKL, May 3, 2018
    #3
  4. Online

    timtower Administrator Administrator Moderator

    @KarimAKL Like I said, you have a plugin variable, it can be null.
     
    timtower, May 3, 2018
    #4
  5. Offline

    KarimAKL

    @timtower Sorry but i don't know what a "plugin variable" is. :/
     
    KarimAKL, May 3, 2018
    #5
  6. Online

    timtower Administrator Administrator Moderator

    @KarimAKL
    plugin.messages.getString(
    One that you made by the looks of it.
     
    timtower, May 3, 2018
    #6
  7. Offline

    KarimAKL

    @timtower This?:
    Code:Java
    1.  
    2. public class CommandWorld implements CommandExecutor {
    3.  
    4.     private Main plugin;
    5.  
    6.     public CommandWorld(Main plugin) {
    7.         this.plugin = plugin;
    8.         plugin.getCommand("world").setExecutor(this);
    9.     }
    10.  
     
    KarimAKL, May 3, 2018
    #7
  8. Online

    timtower Administrator Administrator Moderator

    @KarimAKL Yes, that one, now post your full onEnable and full CommandWorld class please
     
    timtower, May 3, 2018
    #8
  9. Offline

    KarimAKL

    @timtower This is my full onEnable:
    Code:Java
    1.  
    2. @Override
    3.     public void onEnable() {
    4.         if (!getDataFolder().exists()) {
    5.             getDataFolder().mkdirs();
    6.             if (!messagesFile.exists()) {
    7.                 this.saveResource("messages.yml", false);
    8.             }
    9.             new CommandWorld(this);
    10.         } else {
    11.             if (!messagesFile.exists()) {
    12.                 this.saveResource("messages.yml", false);
    13.             }
    14.             new CommandWorld(this);
    15.         }
    16.     }
    17.  

    And this is my full CommandWorld class:
    Code:Java
    1.  
    2. public class CommandWorld implements CommandExecutor {
    3.  
    4.     private Main plugin;
    5.  
    6.     public CommandWorld(Main plugin) {
    7.         this.plugin = plugin;
    8.         plugin.getCommand("world").setExecutor(this);
    9.     }
    10.  
    11.     @Override
    12.     public boolean onCommand(CommandSender sender, Command cmd, String label, String[] args) {
    13.         if (cmd.getName().equalsIgnoreCase("world")) {
    14.             if (!(sender instanceof Player)) {
    15.                 sender.sendMessage(plugin.messages.getString("World.player-only"));
    16.                 return true;
    17.             } else {
    18.                 Player p = (Player) sender;
    19.                 String world = p.getWorld().getName();
    20.                 p.sendMessage(ChatColorUtil.chat(plugin.messages.getString("World.message").replace("{world}", world)));
    21.             }
    22.         }
    23.         return false;
    24.     }
    25.  
    26. }
    27.  
     
    KarimAKL, May 3, 2018
    #9
  10. Online

    timtower Administrator Administrator Moderator

    @KarimAKL Then messages is null.
    I believe that we said to load the configs in the onEnable, not before that.
    And you have nested things that have no need to be nested.
     
    timtower, May 3, 2018
    #10
  11. Offline

    KarimAKL

    @timtower Like this?:
    Code:Java
    1.  
    2. @Override
    3.     public void onEnable() {
    4.         if (!getDataFolder().exists()) {
    5.             getDataFolder().mkdirs();
    6.             if (!messagesFile.exists()) {
    7.                 this.saveResource("messages.yml", false);
    8.                 try {
    9.                     this.messages.save(messagesFile);
    10.                     this.messages.load(messagesFile);
    11.                 } catch (IOException | InvalidConfigurationException e) {
    12.                     e.printStackTrace();
    13.                 }
    14.             }
    15.             new CommandWorld(this);
    16.         } else {
    17.             if (!messagesFile.exists()) {
    18.                 this.saveResource("messages.yml", false);
    19.                 try {
    20.                     this.messages.save(messagesFile);
    21.                     this.messages.load(messagesFile);
    22.                 } catch (IOException | InvalidConfigurationException e) {
    23.                     e.printStackTrace();
    24.                 }
    25.             }
    26.             new CommandWorld(this);
    27.         }
    28.     }
    29.  

    I just tried it and it still comes with the same error, so it's probably not like that. :7 Also, what does "nested" mean?
     
    KarimAKL, May 3, 2018
    #11
  12. Online

    timtower Administrator Administrator Moderator

    @KarimAKL And now without the nested mess.
    Because when the file does exist then you never load anything.

    And nested is having { in a { in a {
     
    timtower, May 3, 2018
    #12
  13. Offline

    KarimAKL

    @timtower Like this?:
    Code:Java
    1.  
    2. @Override
    3.     public void onEnable() {
    4.         if (!getDataFolder().exists()) {
    5.             getDataFolder().mkdirs();
    6.             if (!messagesFile.exists()) {
    7.                 this.saveResource("messages.yml", false);
    8.             }
    9.             try {
    10.                 this.messages.save(messagesFile);
    11.                 this.messages.load(messagesFile);
    12.             } catch (IOException | InvalidConfigurationException e) {
    13.                 e.printStackTrace();
    14.             }
    15.             new CommandWorld(this);
    16.         } else {
    17.             if (!messagesFile.exists()) {
    18.                 this.saveResource("messages.yml", false);
    19.             }
    20.             try {
    21.                 this.messages.save(messagesFile);
    22.                 this.messages.load(messagesFile);
    23.             } catch (IOException | InvalidConfigurationException e) {
    24.                 e.printStackTrace();
    25.             }
    26.             new CommandWorld(this);
    27.         }
    28.     }
    29.  

    EDIT: What about this?:
    Code:Java
    1.  
    2. @Override
    3.     public void onEnable() {
    4.         if (!getDataFolder().exists()) {
    5.             getDataFolder().mkdirs();
    6.         }
    7.         if (!messagesFile.exists()) {
    8.             this.saveResource("messages.yml", false);
    9.         }
    10.         try {
    11.             this.messages.save(messagesFile);
    12.             this.messages.load(messagesFile);
    13.         } catch (IOException | InvalidConfigurationException e) {
    14.             e.printStackTrace();
    15.         }
    16.         new CommandWorld(this);
    17.     }
    18.  
     
    KarimAKL, May 3, 2018
    #13
  14. Online

    timtower Administrator Administrator Moderator

    @KarimAKL You don't need to save messages, and you are still missing the initialization of messagesFile in the onEnable.
     
    timtower, May 3, 2018
    #14
  15. Offline

    KarimAKL

    @timtower Okay so i remove the "this.messages.save" and then how would i add the initialization of messagesFile?
     
    KarimAKL, May 3, 2018
    #15
  16. Online

    timtower Administrator Administrator Moderator

    timtower, May 3, 2018
    #16
  17. Offline

    KarimAKL

    @timtower I need to put this:
    Code:Java
    1.  
    2. public File messagesFile = new File(this.getDataFolder() + "messages.yml");
    3. public FileConfiguration messages = YamlConfiguration.loadConfiguration(messagesFile);
    4.  

    into the onEnable then?
     
    KarimAKL, May 3, 2018
    #17
  18. Online

    timtower Administrator Administrator Moderator

    timtower, May 3, 2018
    #18
  19. Offline

    KarimAKL

    @timtower You mean like this?:
    Code:Java
    1.  
    2. public File messagesFile;
    3. public FileConfiguration messages;
    4.  
    5. @Override
    6. public void onEnable() {
    7.     messagesFile = new File(this.getDataFolder() + "messages.yml");
    8.     messages = YamlConfiguration.loadConfiguration(messagesFile);
    9.     if (!getDataFolder().exists()) {
    10.         getDataFolder().mkdirs();
    11.     }
    12.     if (!messagesFile.exists()) {
    13.         this.saveResource("messages.yml", false);
    14.     }
    15.     try {
    16.         this.messages.load(messagesFile);
    17.     } catch (IOException | InvalidConfigurationException e) {
    18.         e.printStackTrace();
    19.     }
    20.     new CommandWorld(this);
    21. }
    22.  
     
    KarimAKL, May 3, 2018
    #19
  20. Online

    timtower Administrator Administrator Moderator

    @KarimAKL
    messages = YamlConfiguration.loadConfiguration(messagesFile);
    That line needs to be after the saveResource, and then you can also remove the
    try {
    this.messages.load(messagesFile);
    } catch (IOException | InvalidConfigurationException e) {
    e.printStackTrace();
    }
     
    timtower, May 3, 2018
    #20
  21. Offline

    KarimAKL

    @timtower Okay, will try to do that now. :)
    EDIT: Still comes with the same error. :/
    Here is the code:
    Code:Java
    1.  
    2. public File messagesFile;
    3. public FileConfiguration messages;
    4.  
    5. @Override
    6. public void onEnable() {
    7.     messagesFile = new File(this.getDataFolder() + "messages.yml");
    8.     if (!getDataFolder().exists()) {
    9.         getDataFolder().mkdirs();
    10.     }
    11.     if (!messagesFile.exists()) {
    12.         this.saveResource("messages.yml", false);
    13.         messages = YamlConfiguration.loadConfiguration(messagesFile);
    14.     }
    15.     new CommandWorld(this);
    16. }
    17.  
     
    Last edited by a moderator: May 3, 2018
    KarimAKL, May 3, 2018
    #21
  22. Online

    timtower Administrator Administrator Moderator

    @KarimAKL And why is the loadConfiguration in an if statement?
     
    timtower, May 3, 2018
    #22
  23. Offline

    KarimAKL

    @timtower Whoops. :p Like this?:
    Code:Java
    1.  
    2. public File messagesFile;
    3. public FileConfiguration messages;
    4.  
    5. @Override
    6. public void onEnable() {
    7.     messagesFile = new File(this.getDataFolder() + "messages.yml");
    8.     if (!getDataFolder().exists()) {
    9.         getDataFolder().mkdirs();
    10.     }
    11.     if (!messagesFile.exists()) {
    12.         this.saveResource("messages.yml", false);
    13.     }
    14.     messages = YamlConfiguration.loadConfiguration(messagesFile);
    15.     new CommandWorld(this);
    16. }
    17.  

    EDIT: I just tried that and i still comes with the error, either i did something wrong or i still need to do something. :/
     
    KarimAKL, May 3, 2018
    #23
  24. Online

    timtower Administrator Administrator Moderator

    @KarimAKL Then find out what is null, it is plugin? It is messages? Is it the string itself?
     
    timtower, May 3, 2018
    #24
  25. Offline

    KarimAKL

    @timtower I don't know. :/
    Error:
    Code:
    [10:58:55 INFO]: Karim09 issued server command: /world
[10:58:55 ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'world' in plugin WorldTeller v1.0
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46) ~[spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:141) ~[spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at org.bukkit.craftbukkit.v1_8_R3.CraftServer.dispatchCommand(CraftServer.java:641) ~[spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at net.minecraft.server.v1_8_R3.PlayerConnection.handleCommand(PlayerConnection.java:1162) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at net.minecraft.server.v1_8_R3.PlayerConnection.a(PlayerConnection.java:997) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at net.minecraft.server.v1_8_R3.PacketPlayInChat.a(PacketPlayInChat.java:45) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at net.minecraft.server.v1_8_R3.PacketPlayInChat.a(PacketPlayInChat.java:1) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at net.minecraft.server.v1_8_R3.PlayerConnectionUtils$1.run(SourceFile:13) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.8.0_161]
        at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.8.0_161]
        at net.minecraft.server.v1_8_R3.SystemUtils.a(SourceFile:44) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:715) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:374) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:654) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:557) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_161]
Caused by: java.lang.NullPointerException
        at me.karim.worldteller.commands.CommandWorld.onCommand(CommandWorld.java:29) ~[?:?]
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) ~[spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]
        ... 15 more
     
    KarimAKL, May 3, 2018
    #25
  26. Online

    timtower Administrator Administrator Moderator

    @KarimAKL Then find out!
    Add print statements!
    The log won't tell you everything.
     
    timtower, May 3, 2018
    #26
  27. Offline

    KarimAKL

    @timtower I see, will try to put some messages in between then.
    EDIT: I just tried doing this:
    Code:Java
    1.  
    2. public File messagesFile;
    3. public FileConfiguration messages;
    4.  
    5. @Override
    6. public void onEnable() {
    7.     messagesFile = new File(this.getDataFolder() + "messages.yml");
    8.     if (!getDataFolder().exists()) {
    9.         getDataFolder().mkdirs();
    10.         Bukkit.getConsoleSender().sendMessage(ChatColorUtil.chat("Main onEnable mkdirs"));
    11.     }
    12.     if (!messagesFile.exists()) {
    13.         this.saveResource("messages.yml", false);
    14.         Bukkit.getConsoleSender().sendMessage(ChatColorUtil.chat("Main onEnable saveResource"));
    15.     }
    16.     messages = YamlConfiguration.loadConfiguration(messagesFile);
    17.     new CommandWorld(this);
    18.     Bukkit.getConsoleSender().sendMessage(ChatColorUtil.chat("Main onEnable"));
    19. }
    20.  

    But the messages didn't get send to the console, what would that mean? Maybe that the plugin didn't start up correctly or something?
     
    Last edited by a moderator: May 3, 2018
    KarimAKL, May 3, 2018
    #27
  28. Online

    timtower Administrator Administrator Moderator

    @KarimAKL
    Code:
    public File messagesFile;
public FileConfiguration messages;
@Override
public void onEnable() {
   System.out.println("onEnable 1");
  messagesFile = new File(this.getDataFolder() + "messages.yml");
   System.out.println("onEnable 2");
  if (!getDataFolder().exists()) {
     System.out.println("onEnable 3");
  getDataFolder().mkdirs();
     System.out.println("onEnable 4");
  }
   System.out.println("onEnable 5");
  if (!messagesFile.exists()) {
     System.out.println("onEnable 5");
  this.saveResource("messages.yml", false);
     System.out.println("onEnable 6");
  }
   System.out.println("onEnable 7");
  messages = YamlConfiguration.loadConfiguration(messagesFile);
   System.out.println("onEnable 8");
  new CommandWorld(this);
   System.out.println("onEnable 9");
}
    Try that one, indentation is messed up because you are using spaces and I am using tabs.
     
    timtower, May 3, 2018
    #28
  29. Offline

    KarimAKL

    @timtower I just tried using the "System.out.println("onEnable 1")" etc and all of them got send in the console, so what now?
     
    KarimAKL, May 3, 2018
    #29
  30. Online

    timtower Administrator Administrator Moderator

    @KarimAKL Then you print the values of the things you use, so messages and the string inside messages
     
    timtower, May 3, 2018
    #30
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