Please need help in Serialization

[gurpeet singh]

Please refer example on page 467 of Kathy Seirra and Bert Bates SCJP 6 Book. following is a part of the code from the example on the aforementioned page.

CODE LISTING

private void writeObject(ObjectOutputStream os) {
// throws IOException { // 1
try {
os.defaultWriteObject(); // 2
[b]os.writeInt(theCollar.getCollarSize()); // 3[/b]
} catch (Exception e) { e.printStackTrace(); }
}
private void readObject(ObjectInputStream is) {
// throws IOException, ClassNotFoundException { // 4
try {
is.defaultReadObject(); // 5
theCollar = new Collar(is.readInt()); // 6
} catch (Exception e) { e.printStackTrace(); }
}
}

My question is that when we are serializing the dog object the serialization system calls the callback private writeObject method and passed it the ObjectOutputStream. but when we did os.writeInt(theCollar.getCollarSize()); how did it know which Dog's object Collar we are talking about, because we are not passing any dog reference explicitly or implicitly. ???

[Matthew Brown]

That method is added to the Dog class. So there is an implicit Dog reference: this.

[Helen Ma]

As a friendly reminder, it is good to learn more about object serialization/deserialization. But this objective has been removed from OCJP 6.0 exam.

[gurpeet singh]

thanks for the reply Helen....but the topic Serialization is given in the SCJP 6 K&B book.......Can you please give me the source of updated objectives/syllabus for OCJP 6? thanks

[John Jai]

Check for SCJP 1.6 (310-065) in our SCJP-FAQ_Objectives

[Helen Ma]

Even though this objective is removed from the exam, object serialization and deserialization are very useful in Java remote method invokcation (RMI).
When a client passes an object to a server over the network, the object has to be serialized. When the server receives it, it has to deserialize it.