Solved Strange HashMap/YAML error.

Hey there,

While trying to make a simple leveling type plugin I've encountered a small bug. After spending countless hours trying to figure it out myself, I've given up. I come here, seeking guidance.

First of all, here is the error itself.

The Error (open) The Error (close)

Code:

 
2013-04-12 13:47:41 [INFO] [MinecraftLegend] Disabling MinecraftLegend v1.0
2013-04-12 13:47:41 [INFO] 229 recipes
2013-04-12 13:47:41 [INFO] [MinecraftLegend] Loading MinecraftLegend v1.0
2013-04-12 13:47:41 [INFO] [MinecraftLegend] Enabling MinecraftLegend v1.0
2013-04-12 13:47:41 [INFO] Server permissions file permissions.yml is empty, ignoring it
2013-04-12 13:47:41 [INFO] CONSOLE: Reload complete.
2013-04-12 13:47:43 [SEVERE] Could not pass event EntityDeathEvent to MinecraftLegend v1.0
org.bukkit.event.EventException
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:427)
at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:477)
at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:462)
at org.bukkit.craftbukkit.v1_5_R2.event.CraftEventFactory.callEntityDeathEvent(CraftEventFactory.java:318)
at net.minecraft.server.v1_5_R2.EntityChicken.dropDeathLoot(EntityChicken.java:105)
at net.minecraft.server.v1_5_R2.EntityLiving.die(EntityLiving.java:909)
at net.minecraft.server.v1_5_R2.EntityLiving.damageEntity(EntityLiving.java:766)
at net.minecraft.server.v1_5_R2.EntityAnimal.damageEntity(SourceFile:119)
at net.minecraft.server.v1_5_R2.EntityHuman.attack(EntityHuman.java:854)
at net.minecraft.server.v1_5_R2.PlayerConnection.a(PlayerConnection.java:1102)
at net.minecraft.server.v1_5_R2.Packet7UseEntity.handle(SourceFile:36)
at net.minecraft.server.v1_5_R2.NetworkManager.b(NetworkManager.java:292)
at net.minecraft.server.v1_5_R2.PlayerConnection.d(PlayerConnection.java:110)
at net.minecraft.server.v1_5_R2.ServerConnection.b(SourceFile:35)
at net.minecraft.server.v1_5_R2.DedicatedServerConnection.b(SourceFile:30)
at net.minecraft.server.v1_5_R2.MinecraftServer.r(MinecraftServer.java:578)
at net.minecraft.server.v1_5_R2.DedicatedServer.r(DedicatedServer.java:225)
at net.minecraft.server.v1_5_R2.MinecraftServer.q(MinecraftServer.java:474)
at net.minecraft.server.v1_5_R2.MinecraftServer.run(MinecraftServer.java:407)
at net.minecraft.server.v1_5_R2.ThreadServerApplication.run(SourceFile:573)
Caused by: java.lang.NullPointerException
at me.pers2981.MinecraftLegend.EntityLis.onMobDeath(EntityLis.java:40)
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 org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:425)
... 20 more

Code:

Caused by: java.lang.NullPointerException
at me.pers2981.MinecraftLegend.EntityLis.onMobDeath(EntityLis.java:40)

I've navigated to "EntityLis.java:40" to find the following.

Code:

Integer CurExp = plugin.PlayerExp.get(player.getName());

This code creates a new variable that takes the value from a hashmap. This variable is the players current experience.

I'm really not sure what's causing this error, any ideas?

On a side note, while I was trying to debug the problem myself, I stumbled across the following.

Main Listener Reg code (open) Main Listener Reg code (close)

Code:

pm.registerEvents(new EntityLis(null), this);

EntityListener code (open) EntityListener code (close)

Code:

@EventHandler
public void onMobDeath(EntityDeathEvent event)
{
Entity entity = event.getEntity();
if(entity instanceof LivingEntity) {
LivingEntity living = (LivingEntity) entity;
living.setCustomName(ChatColor.DARK_GREEN + "" + ChatColor.RED + "█████████");
living.setCustomNameVisible(true);
if (event.getEntity().getKiller() != null)
{
if (event.getEntity().getKiller() instanceof Player)
{
Player player = event.getEntity().getKiller();
Integer CurExp = plugin.PlayerExp.get(player.getName());
Integer MaxExp = plugin.PlayerLevel.get(player.getName()) * 100;
Integer CurLvl = plugin.PlayerLevel.get(player.getName());
 
CurExp = CurExp + 10;
 
if (CurExp >= MaxExp)
{
plugin.PlayerLevel.remove(player.getName());
plugin.PlayerExp.remove(player.getName());
CurLvl = CurLvl + 1;
CurExp = 0;
plugin.PlayerLevel.put(player.getName(),CurExp);
plugin.PlayerExp.put(player.getName(),CurExp);
 
}
}
}
}
}

Code:

private MinecraftLegend plugin; 
 
public EntityLis(MinecraftLegend plugin)
    {
        this.plugin = plugin;
        
    }

I'm not sure if this would be some how causing the HashMap's to be 'null'?

Any advice/guidance is greatly appreciated.

Thanks
Jacob

 

The error means that the HashMap does not contain the player.getName() key. Just use a != null check to fix it.

EDIT:
Why do you put this on null?
pm.registerEvents(new EntityLis(null), this);

You could better use
pm.registerEvents(new EntityLis(this), this);