Debug Login

package hyg.hydrosis.debug;
import org.bukkit.plugin.java.JavaPlugin;


public class Main extends JavaPlugin{

    public int counter = 0;

    @Override
    public void onEnable()
    {
        new Listeners(this);
    }

}
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package hyg.hydrosis.debug;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.player.PlayerLoginEvent;
import org.bukkit.event.player.PlayerLoginEvent.Result;


public class Listeners implements Listener{

    Main plugin;

    public Listeners(Main plugin)
    {
        this.plugin = plugin;
        plugin.getServer().getPluginManager().registerEvents(this, plugin);
    }

    @EventHandler
    public void onJoin(PlayerLoginEvent event)
    {
        if(plugin.counter%2==1)
            event.disallow(Result.KICK_BANNED, "Not an even login!");
        plugin.counter++;
    }

}