static variable and Serialization.

[Abimaran Kugathasan]

I got it from Exam Lab 01. static variable aren't Serializable. When I serialize the object whose class has static variable. Have look the below code:

import java.io.*;

public class AB implements Serializable {
	int a = 1; static int b = 2; transient int c = 3;
	AB(int a,int b, int c)	{
		this.a = a; this.b = b; this.c = c;
	}

	public static void main(String[] args) throws Exception	{
		AB ob = new AB(4,5,6);
		new ObjectOutputStream(new FileOutputStream("A.ser")).writeObject(ob);
		AB ob2 = (AB)new ObjectInputStream(new FileInputStream("A.ser")).readObject();
		System.out.print(ob2.a + ", " + ob2.b + ", " + ob2.c);
	}
}

Output : 4, 5, 0.
How is it possible? Thanks in Advanced!

[Ankit Garg]

The value of a was serialized, so it was retrieved when the instance was read, the value of b was not touched during serialization/deserialization. The value of c was reset since it was not serialized, so it was given the default value for its datatype i.e. 0 during deserialization. Also remember serialization is not on the exam now...

[Jim Hoglund]

Caution : If the JVM is stopped and restarted while the data is saved,
the static variables will be reinitialized too, (like the transients) when
the class is loaded.

Jim ... ...

[Abimaran Kugathasan]

Ankit Garg wrote:The value of a was serialized, so it was retrieved when the instance was read, the value of b was not touched during serialization/deserialization. The value of c was reset since it was not serialized, so it was given the default value for its datatype i.e. 0 during deserialization. Also remember serialization is not on the exam now...

Thanks for the reply. But the value of b is 5 after deserialized? That's my problem.....

[pete stein]

Abimaran Kugathasan wrote:
Thanks for the reply. But the value of b is 5 after deserialized? That's my problem.....

I think that it has nothing to do with serialization / deserialization and all to do that you changed the value of b in the main method and it remains changed throughout the program.

[Abimaran Kugathasan]

pete stein wrote:
I think that it has nothing to do with serialization / deserialization and all to do that you changed the value of b in the main method and it remains changed throughout the program.

Thanks pete stein. Now I got it.

import java.io.*;

public class ABC implements Serializable {
	int a = 1; static int b = 2; transient int c = 3;
	ABC(int a,int b, int c)	{
		this.a = a; this.b = b; this.c = c;
	}

	public static void main(String[] args) throws Exception	{
		ABC ob = new ABC(4,5,6);
		ABC ob3 = new ABC(6,7,8);
		new ObjectOutputStream(new FileOutputStream("A.ser")).writeObject(ob);
		ABC ob2 = (ABC)new ObjectInputStream(new FileInputStream("A.ser")).readObject();
		System.out.print(ob2.a + ", " + ob2.b + ", " + ob2.c);
		System.gc();
		System.out.print(ob.a + ", " + ob.b + ", " + ob.c);
	}
}

Thanks!

[pete stein]

Abimaran Kugathasan wrote:
Thanks pete stein. Now I got it.

Don't thank me as I was just repeating what Ankit Garg already posted.