Development Assistance Why it doesn't work ?

Code:

Code:

//FileManager
public class FileManager {
private static File df = Main.instance.getDataFolder();
private static File msg = new File(df, "messages.yml");
private static YamlConfiguration msgYml;
public static void checkDataFolder() {
if(!df.exists()) {
df.mkdir();
}
}
public static void checkMsg() {
if(!msg.exists()) {
try {
msg.createNewFile();
msgYml = YamlConfiguration.loadConfiguration(msg);
msgYml.set("EXP", "2");
} catch (IOException e) {
e.printStackTrace();
}
try {
msgYml.save(msg);
} catch (IOException e) {
e.printStackTrace();
}
}
msgYml = YamlConfiguration.loadConfiguration(msg);
}
public static void saveMsg() {
try {
msgYml.save(msg);
} catch (IOException e) {
e.printStackTrace();
}
}
public static YamlConfiguration getMsg() {
return msgYml;
}
public static void reloadMsg() {
msgYml = YamlConfiguration.loadConfiguration(msg);
}
}
// Main
public class Main extends JavaPlugin {
public static Main plugin;
public static Main instance;
@Override
public void onEnable() {
instance = this;
FileManager.checkDataFolder();
FileManager.checkMsg();
getCommand("exp").setExecutor(new ExpCmd(this));
}
}
// ExpCmd
public class UleczCmd implements CommandExecutor {
public UleczCmd(Main plugin) {}
@Override
public boolean onCommand(CommandSender sender, Command cmd,String l, String[] args) {
Player p = (Player) sender;
int EXP = FileManager.getMsg().getInt("EXP");
if(cmd.getName().equalsIgnoreCase("exp")) {
p.setExp(EXP);
p.sendMessage("Healted + " + EXP);
}
return false;
}
}

Console:

Code:

[22:46:09] [Server thread/ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'exp' in plugin MyTools v0.1
    at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46) ~[spigot.jar:git-Spigot-1644]
    at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:181) ~[spigot.jar:git-Spigot-1644]
    at org.bukkit.craftbukkit.v1_7_R4.CraftServer.dispatchCommand(CraftServer.java:767) ~[spigot.jar:git-Spigot-1644]
    at net.minecraft.server.v1_7_R4.PlayerConnection.handleCommand(PlayerConnection.java:1043) [spigot.jar:git-Spigot-1644]
    at net.minecraft.server.v1_7_R4.PlayerConnection.a(PlayerConnection.java:880) [spigot.jar:git-Spigot-1644]
    at net.minecraft.server.v1_7_R4.PacketPlayInChat.a(PacketPlayInChat.java:28) [spigot.jar:git-Spigot-1644]
    at net.minecraft.server.v1_7_R4.PacketPlayInChat.handle(PacketPlayInChat.java:65) [spigot.jar:git-Spigot-1644]
    at net.minecraft.server.v1_7_R4.NetworkManager.a(NetworkManager.java:186) [spigot.jar:git-Spigot-1644]
    at net.minecraft.server.v1_7_R4.ServerConnection.c(ServerConnection.java:81) [spigot.jar:git-Spigot-1644]
    at net.minecraft.server.v1_7_R4.MinecraftServer.v(MinecraftServer.java:734) [spigot.jar:git-Spigot-1644]
    at net.minecraft.server.v1_7_R4.DedicatedServer.v(DedicatedServer.java:289) [spigot.jar:git-Spigot-1644]
    at net.minecraft.server.v1_7_R4.MinecraftServer.u(MinecraftServer.java:584) [spigot.jar:git-Spigot-1644]
    at net.minecraft.server.v1_7_R4.MinecraftServer.run(MinecraftServer.java:490) [spigot.jar:git-Spigot-1644]
    at net.minecraft.server.v1_7_R4.ThreadServerApplication.run(SourceFile:628) [spigot.jar:git-Spigot-1644]
Caused by: java.lang.NullPointerException
    at pl.arlait.MyTools.Main.onCommand(Main.java:26) ~[?:?]
    at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) ~[spigot.jar:git-Spigot-1644]
    ... 13 more

 

Moved to Plugin Development.

 

http://bukkit.org/threads/how-to-re...ubleshoot-your-own-plugins-by-yourself.32457/

I also suggest you remove those needless static modifiers.