Serialization.

[Rohit Ramachandran]

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

public class Tester implements Serializable{

transient int x = 5;

public static void main(String[] args) {
Tester tester1 = new Tester();
try {
ObjectOutputStream os = new ObjectOutputStream(
new FileOutputStream("data.txt"));
os.writeObject(tester1);
os.close();
System.out.print(++tester1.x + " ");
ObjectInputStream is = new ObjectInputStream(new FileInputStream(
"data.txt"));
Tester tester2 = (Tester) is.readObject();
is.close();
System.out.println(tester2.x);
} catch (Exception x) {
System.out.println("Exception thrown");
}
}

}

Output: 6 0

I don't get it. Why is it 0?

[Wouter Oet]

Please UseCodeTags when posting code. It will highlight your code and make it much easier to read. It probably will also increase the number of people helping you.

Why would it be 0? You have written the object to the file but that doesn't change anything to the object itself. Nothing gets changed. The value gets incremented and printed.

Although it is nice to know how serialization works, it is no longer on the current exam.

[Komal Arora]

Transient variables are NOT serialized. tester1 is written, but as wouter said

You have written the object to the file but that doesn't change anything to the object itself. Nothing gets changed. The value gets incremented and printed.

In the second case, when you READ back the object, since the state was declared transient, the state was NOT saved and hence we get 0 as the output.

[Rahul Saple]

Also, changing the tranisent nature of the field would lead to the answer being 5 in the desrialized output, as you are incrementing the value after it is written out to the file.