Solved java.lang.ClassCastException in Plugin

Hello,

I've just written my first plugin, and it would seem to work (except for the PlayerChatEvent deprecation, but it should still work), but I get this in the console when it tries to start:

Code:

Could not load 'plugins\GamemodeDetector.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.ClassCastException: class com.vemacs.GamemodeDetector.GamemodeDetector
    at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:154)
    at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:305)
    at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:230)
    at org.bukkit.craftbukkit.CraftServer.loadPlugins(CraftServer.java:227)
    at org.bukkit.craftbukkit.CraftServer.<init>(CraftServer.java:203)
    at net.minecraft.server.ServerConfigurationManagerAbstract.<init>(ServerConfigurationManagerAbstract.java:50)
    at net.minecraft.server.ServerConfigurationManager.<init>(SourceFile:11)
    at net.minecraft.server.DedicatedServer.init(DedicatedServer.java:105)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:378)
    at net.minecraft.server.ThreadServerApplication.run(SourceFile:539)
Caused by: java.lang.ClassCastException: class com.vemacs.GamemodeDetector.GamemodeDetector
    at java.lang.Class.asSubclass(Unknown Source)
    at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:144)
    ... 9 more

Here's my plugin source (ignore the fact that I don't own vemacs.com, I just want to get it working):

Code:

package com.vemacs.GamemodeDetector;
 
import org.bukkit.Bukkit;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.player.PlayerChatEvent;
 
@SuppressWarnings("deprecation")
public class GamemodeDetector implements Listener {
 
    private GamemodeDetector plugin;
 
    public GamemodeDetector(GamemodeDetector instance) {
        plugin = instance;
    }
 
        @EventHandler
    public void onPlayerMessage(PlayerChatEvent E) {
            Player player = E.getPlayer();
            String playerName = player.getName();
            String message = E.getMessage().toLowerCase();
            if(message.contains("/gamemode")){
            Bukkit.broadcastMessage( playerName + "used the /gamemode command!");
        }
}
}

And here's my plugin.yml:

Code:

name: GamemodeDetector
main: com.vemacs.GamemodeDetector.GamemodeDetector
version: 1.0

The plugin.yml is in the package tree, not in the source tree. What's going wrong?
Thanks for the help. I'm running the latest craftbukkit recommended.

The project is attached (gamemodedetector.zip).

 

Your plugin is not a java plugin,
Please refer to the documentation. Specifically you failed here