Question

I have class SuperYo extending class Persona, like this:

public class SuperYo extends Persona {

   private NotSerializableObj obj1
   private NotSerializableObj obj2
   private NotSerializableObj obj3

}

public class Persona {

   private SerializableObj sObj1
   private SerializableObj sObj2
   private SerializableObj sObj3

}

The thing is, that I add to a LinkedList an Instance of Persona from SuperYo:

LinkedList<Persona> list = new LinkedList<Persona>();
list.add((Persona) superYo);

It adds it as a SuperYo Object! With all the NonSerializableObjs on it… and thus, cant be sent from a Socket :(.

So, the question is… is there any way of “downcasting” an object to its father class, so its attributtes are non present?

Thanks!

Answer 1

Implement readObject and writeObject in SuperYo as below:

 private void writeObject(ObjectOutputStream outStream) throws IOException {
    //write attributes from PersonYo only
    outStream.defaultWriteObject();
    outStream.writeObject(sObj1);
    outStream.writeObject(sObj2);
    outStream.writeObject(sObj2);
 }

private void readObject(ObjectInputStream inStream) throws IOException,
                                                          ClassNotFoundException {
    //read attributes from PersonYo only
    inStream.defaultReadObject();
    sObj1= (SerializableObj)inStream.readObject();
    sObj2= (SerializableObj)inStream.readObject();
    sObj3= (SerializableObj)inStream.readObject();
}

Once you do this, there will be no need of down-casting. Also you may have better control on other non-serializable attributes in the object.