Question

I use a Socket-based connection between Client and server with ObjectOutputStream.

The objects serialized and exchanged have this structure:

public class RichiestaSalvataggioArticolo implements Serializable {

        private ArticoloDati articolo;

        public RichiestaSalvataggioArticolo(ArticoloDati articolo) {
                this.articolo = articolo;

        }

        @Override
        public void ricevi(GestoreRichieste gestore) throws Exception {
                gestore.interpreta(this);                    
        }


        public ArticoloDati getArticolo() {
                return articolo;
        }

}

the issue is that when I try to exchange messages between C/S with incapsulated content very similar (ArticoloDati whom differ only in 2 fields out of 10), the Client sends an ArticoloDati, but the Server receives the previous one.

Does the ObjectOutputStream implement some kind of cache or memory between the calls, that fails to recognize that my 2 objects are different because they are very similar?

Answer 1

You need to disable “back-references” in serialization, so use ObjectOutputStream.writeUnshared.

Writes an “unshared” object to the ObjectOutputStream. This method is identical to writeObject, except that it always writes the given object as a new, unique object in the stream (as opposed to a back-reference pointing to a previously serialized instance).

It’s good practice to couple this with ObjectInputStream.readUnshared in some cases — this one included.