Non sérialisable objet d'erreur tout en travaillant sur Memcache

Salut tout le monde je travaillais avec memcache, et lorsque j'ai compilé ce code je l'ai eu suite à des erreurs.

2010-07-09 10:35:53.499 INFO net.spy.memcached.MemcachedConnection:  Added {QA sa=localhost/127.0.0.1:11211, #Rops=0, #Wops=0, #iq=0, topRop=null, topWop=null, toWrite=0, interested=0} to connect queue
2010-07-09 10:35:53.520 INFO net.spy.memcached.MemcachedConnection:  Connection state changed for sun.nio.ch.SelectionKeyImpl@7fdcde
Exception in thread "main" java.lang.IllegalArgumentException: Non-serializable object
 at net.spy.memcached.transcoders.BaseSerializingTranscoder.serialize(BaseSerializingTranscoder.java:86)
 at net.spy.memcached.transcoders.SerializingTranscoder.encode(SerializingTranscoder.java:135)
 at net.spy.memcached.MemcachedClient.asyncStore(MemcachedClient.java:301)
 at net.spy.memcached.MemcachedClient.set(MemcachedClient.java:691)
 at def.Tweet.main(Tweet.java:23)
Caused by: java.io.NotSerializableException: def.User
 at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1173)
 at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:343)
 at net.spy.memcached.transcoders.BaseSerializingTranscoder.serialize(BaseSerializingTranscoder.java:81)
 ... 4 more

J'ai réussi à la fixer avec de la conversion de l'Utilisateur de la classe toString mais je ne veux pas utiliser la méthode toString.Je veux juste utiliser ma classe pour ajouter et obtenir mwethods. Comment puis-je résoudre ce problème?
Voici le code que j'utilise.

package def;

import java.io.IOException;
import java.io.Serializable;
import java.net.InetSocketAddress;

import net.spy.memcached.MemcachedClient;

public class Tweet {
  private static User user;
  private static Message message;
  private static Followers follower;

public static void main(String[] args) throws Exception {
 try{
     user = new User(1,"Mehmet Özer","asd","127.0.0.1","True","Onine");
  //String deneme = user.toString();
  MemcachedClient c=new MemcachedClient(new InetSocketAddress("localhost", 11211));


  //Store a value (async) for one hour

  c.set(user.userKey, 3600, user);
  System.out.println(c.get(user.userKey));

    }
  catch(IOException ex) {
        ex.printStackTrace();
    }
}
}

Désolé , j'ai oublié l'Utilisateur de la classe, je suis aussi en vous donnant l'Utilisateur de la classe pour m'aider à mieux.

public class User {
    public static String userKey = "UserDB";
    public static int userID ;
    public static String userName;
    public static String password;
    public static String ipAddress;
    public static String isOnline;
    public static String lastActive;

    public User(int userID, String userName, String password, String ipAddress,String isOnline,String lastActive)
    {
        this.userID = userID;
        this.userName = userName;
        this.password = password;
        this.ipAddress = ipAddress;
        this.isOnline = isOnline;
        this.lastActive = lastActive;

    }
    @Override
    public String toString() {
        System.out.println(this.userID);
        System.out.println(this.userName);
        System.out.println(this.password);
        System.out.println(this.ipAddress);
        System.out.println(this.isOnline);
        System.out.println(this.lastActive);

        return super.toString();
    }


    }

OriginalL'auteur mehmetozer | 2010-07-09