Serializing static variables

[Tere Luna]

Hi,

I'm not sure why this following code (it's in one of the questions for SCJP guide in chapter 6)

public class TestSer {
	public static void main(String[] args) {
		SpecialSerial s = new SpecialSerial();
		try {
			ObjectOutputStream os = new ObjectOutputStream(
					new FileOutputStream("myFile"));
			os.writeObject(s);
			os.close();
			System.out.print(++s.z + " ");
			ObjectInputStream is = new ObjectInputStream(new FileInputStream(
					"myFile"));
			SpecialSerial s2 = (SpecialSerial) is.readObject();
			is.close();
			System.out.println(s2.y + " " + s2.z);
		} catch (Exception x) {
			System.out.println("exc");
		}
	}
}

class SpecialSerial implements Serializable {
	transient int y = 7;
	static int z = 9;
}

El resultado es "10 0 10", I guess that the static variable z was indeed serialized and deserialized or why does it have the value of 10?

Thanks a lot

[Stanley Hataria]

hey if you read this line of code
System.out.print(++s.z + " ");

where it increments the static variable. also static variable is for the class so changes are visible everywhere.

[Paul Clapham]

No, static variables aren't serialized. Like Stanley said, first z was 9, then the code incremented it, so now it's 10. If you remove all the code which serializes and deserializes objects from that example you will see the same thing happening.

[Tommy Delson]

Serialization is NOT on the exam as Bert stated, but it's good to learn it.


Static members are not serialized...

See my responses on Serialization for more insight:

https://coderanch.com/t/541339/java-programmer-SCJP/certification/static-members-inherited

https://coderanch.com/t/539469/java-programmer-SCJP/certification/Serialization#2448680

[Tere Luna]

Thanks everyone for your answers. They have been very helpful

[Stanley Hataria]

Hey Paul ,
Can you state what else is not on the exam?
It would be helpful

[Tere Luna]

Yes please, help us identify which topics that are in the guide written by Kathy Sierra and Bert Bates are not in the exam, since they mention almost all the topics are includee

Thanks

[Tommy Delson]

I recommend check out on Oracle website for more information on topics that will be on the exam.

Here is the link you can check out:

http://education.oracle.com/pls/web_prod-plq-dad/db_pages.getpage?page_id=41&p_exam_id=1Z0_853

[Tere Luna]

Thanks you Tommy, I'm checking it out right now

[Naveen Madarapu]

for easy understanding watch this thread

https://coderanch.com/t/544894/java-programmer-SCJP/certification/please-explain-output