Using config related methods from another class

Hello im making mmorpg type plugin and i want spells to use mana. Mana of every player is stored in config and i have created methods removeMana(); and getMana(); they work fine in main class but I have class spelllistener and when i used these methods there, it gives me an error:

Code:

[19:12:06 ERROR]: Could not pass event InventoryClickEvent to mravian v1.0
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:427) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.jav
a:62) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.j
ava:481) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.j
ava:466) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]
        at net.minecraft.server.v1_7_R1.PlayerConnection.a(PlayerConnection.java
:1351) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]
        at net.minecraft.server.v1_7_R1.PacketPlayInWindowClick.a(SourceFile:32)
[craftbukkit.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]
        at net.minecraft.server.v1_7_R1.PacketPlayInWindowClick.handle(SourceFil
e:10) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]
        at net.minecraft.server.v1_7_R1.NetworkManager.a(NetworkManager.java:146
) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]
        at net.minecraft.server.v1_7_R1.ServerConnection.c(SourceFile:134) [craf
tbukkit.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]
        at net.minecraft.server.v1_7_R1.MinecraftServer.u(MinecraftServer.java:6
55) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]
        at net.minecraft.server.v1_7_R1.DedicatedServer.u(DedicatedServer.java:2
50) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]
        at net.minecraft.server.v1_7_R1.MinecraftServer.t(MinecraftServer.java:5
45) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]
        at net.minecraft.server.v1_7_R1.MinecraftServer.run(MinecraftServer.java
:457) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]
        at net.minecraft.server.v1_7_R1.ThreadServerApplication.run(SourceFile:6
17) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]
Caused by: java.lang.IllegalArgumentException: File cannot be null
        at org.apache.commons.lang.Validate.notNull(Validate.java:203) ~[craftbu
kkit.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]
        at org.bukkit.configuration.file.YamlConfiguration.loadConfiguration(Yam
lConfiguration.java:171) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]
        at org.bukkit.plugin.java.JavaPlugin.reloadConfig(JavaPlugin.java:118) ~
[craftbukkit.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]
        at org.bukkit.plugin.java.JavaPlugin.getConfig(JavaPlugin.java:112) ~[cr
aftbukkit.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]
        at com.gmail.blazer.SpellListener.getMana(SpellListener.java:132) ~[?:?]
 
        at com.gmail.blazer.SpellListener.removeMana(SpellListener.java:138) ~[?
:?]
        at com.gmail.blazer.SpellListener.onInventoryClick(SpellListener.java:78
) ~[?:?]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.7.0
_45]
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.7.0
_45]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1
.7.0_45]
        at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.7.0_45]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:425) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.2-b2974jnks]
        ... 13 more

Here are my methods. not sure anything else can help... (lines in error are in these methods)

Code:java

 public Integer getMana(Player p){
Integer mana= getConfig().getInt(p.getName() +".Mana");
 
return mana;
}
public void removeMana(Player p, Integer mana){
 
int ma =getMana(p)-mana;
getConfig().set(p.getName() +".Mana", ma);
}

Any tips? I think something is wrong with getConfig().

 

You need to call getConfig() from a reference to the main class. Pass the singleton instance to your listener when you register your events and then use it from there.

Code:java

//onEnable
getServer().getPluginManager().registerEvents(new SpellListener(this), this);
//in the listener
private final <PluginName> plugin;
public SpellListener(Plugin plugin) {
    this.plugin = plugin;
}
 

You can then call plugin.getConfig()