Serialization

[Sushant Kaushik]

Source - K &B chapter 6, Page 455

class SuperNotSerial{
public static void main (String[] args) {

Dog d = new Dog(35, "Fido");
System.out.println("before: " + d.name + " " + d.weight);
try {
FileOutputStream fs = new FileOutputStream("testSer.ser");
ObjectOutputStream os = new ObjectOutputStream(fs);
os.writeObject(d);
os.close();
} catch (Exception e) { e.printStackTrace(); }
try {
FileInputStream fis = new FileInputStream("testSer.ser");
ObjectInputStream ois = new ObjectInputStream(fis);
d = (Dog) ois.readObject();
ois.close();
} catch (Exception e) { e.printStackTrace(); }
System.out.println("after: " + d.name + " "+ d.weight);

}
}
class Dog extends Animal implements Serializable {
String name;
Dog(int w, String n) {
weight = w; // inherited
name = n; // not inherited
}
}
class Animal{ 
transient int weight = 42;
}

The Output is -
before: Fido 35
after: Fido 42

This is fine as Animal class didn't implement Serializable interface so weight got its intialized value of 42.
My question is if I modify Animal class as -

class Animal implements Serializable{ 
transient int weight = 42;
}

The output is
before: Fido 35
after: Fido 0

Can somebody please explain why in this case I am getting 0 for weight instead of 42?

Thanks,
Sushant

[Arie Prastowo]

if you do not use serialization on parent class, it's attribute will not be serialized no matter you mark it as transient or not.
When you deserialized, the attribute from not serialized parent class will be initialized.
But on serialized parent class, a transient attribute is not serialized or deserialized, so the value is 0 as in default value

[Sushant Kaushik]

Thanks Arie..now it got clarified