PlayerInventoryListener Question - amount of an ItemStack in a Inventory

I need a PlayerListener that issues the amount of a specific ItemStack in a player's inventory.If a specific number is present something should happen. Can someone please give the code for it? I don't understand how listeners works.Thanks

 

Spaces are handy.

 

sorry,
I think there was a problem with the texteditor. I'm sure that I wrote the spaces

 

If you "don't understand how listeners work", please, take the time to read a tutorial on how to get started with Bukkit before asking on the forums...

 

Ok I read the TuT.
(Last time I was on the PluginDevelopmentSite there was no translation of the eventSystem into german; I'm not realy good in reading enlish tutorials)

Now I made this Code:

Code:

package me.dragon252525.speedmining;
 
import org.bukkit.ChatColor;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.player.PlayerPickupItemEvent;
import org.bukkit.inventory.ItemStack;
 
public class SpeedMiningPlayerListener implements Listener {
    public static SpeedMining plugin;
   
    @EventHandler
    public void onPlayerGetItem(PlayerPickupItemEvent event) {
       
        Player p = event.getPlayer();
       
        String selected = plugin.getConfig().getString("Tools.selected");
       
        int amount = plugin.getConfig().getInt("Games." + selected + ".options.amount");
        String itemName = plugin.getConfig().getString("Games." + selected + ".options.itemName");
       
        String p1 = plugin.getConfig().getString("Games." + selected + ".players.1");
        String p2 = plugin.getConfig().getString("Games." + selected + ".players.2");
        String p3 = plugin.getConfig().getString("Games." + selected + ".players.3");
        String p4 = plugin.getConfig().getString("Games." + selected + ".players.4");
        String p5 = plugin.getConfig().getString("Games." + selected + ".players.5");
        String p6 = plugin.getConfig().getString("Games." + selected + ".players.6");
        String p7 = plugin.getConfig().getString("Games." + selected + ".players.7");
        String p8 = plugin.getConfig().getString("Games." + selected + ".players.8");
       
        if (    (p.getName().equalsIgnoreCase(p1)) ||
                (p.getName().equalsIgnoreCase(p2)) ||
                (p.getName().equalsIgnoreCase(p3)) ||
                (p.getName().equalsIgnoreCase(p4)) ||
                (p.getName().equalsIgnoreCase(p5)) ||
                (p.getName().equalsIgnoreCase(p6)) ||
                (p.getName().equalsIgnoreCase(p7)) ||
                (p.getName().equalsIgnoreCase(p8))) {
           
            if (p.getInventory().contains(new ItemStack(264, amount))) {
                plugin.getServer().broadcastMessage(ChatColor.BLUE + "" + ChatColor.BOLD + p.getName() + " hat alle " + amount + " " + itemName + " gefunden!");
                return;
            }
            else {
                return;
            }
           
        }
        else {
            return;
        }
       
    }
}

but when I pick up an item, the Server shows me this error:

Code:

2012-05-01 20:46:15 [SEVERE] Could not pass event PlayerPickupItemEvent to SpeedMining
org.bukkit.event.EventException
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:303)
    at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
    at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:459)
    at net.minecraft.server.EntityItem.a_(EntityItem.java:150)
    at net.minecraft.server.EntityHuman.l(EntityHuman.java:354)
    at net.minecraft.server.EntityHuman.e(EntityHuman.java:346)
    at net.minecraft.server.EntityLiving.F_(EntityLiving.java:447)
    at net.minecraft.server.EntityHuman.F_(EntityHuman.java:159)
    at net.minecraft.server.EntityPlayer.a(EntityPlayer.java:228)
    at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:341)
    at net.minecraft.server.Packet10Flying.handle(SourceFile:126)
    at net.minecraft.server.NetworkManager.b(NetworkManager.java:229)
    at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:113)
    at net.minecraft.server.NetworkListenThread.a(NetworkListenThread.java:78)
    at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:551)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:449)
    at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)
Caused by: java.lang.NullPointerException
    at me.dragon252525.speedmining.SpeedMiningPlayerListener.onPlayerGetItem(SpeedMiningPlayerListener.java:23)
    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:301)
    ... 16 more

where's the Problem?

EDIT by Moderator: merged posts, please use the edit button instead of double posting.