my static int is serialized, WHY?

[adam Lui]

examine this tiny code...

import java.io.*;
public class TestSer {
public static void main(String[] args) {
SpecialSerial s = new SpecialSerial();
try {
ObjectOutputStream os = new ObjectOutputStream(new FileOutputStream("myFile"));
s.z = 33;
System.out.println ("assign value to static z " + s.z);
os.writeObject(s); 
os.close();




ObjectInputStream is = new ObjectInputStream(new FileInputStream("myFile"));
SpecialSerial s2 = (SpecialSerial)is.readObject();
System.out.println(s2.y + " " + s2.z); //s2.z 's value is 33, not 9? isnt static value not saved?
is.close();


} catch (Exception x) 
{System.out.println("exc"); }
}
}
 
class SpecialSerial implements Serializable {
transient int y = 7;
static int z = 9;

}

this may be an illusion, but by the output it looks like the z value of int in specialSerial class is being saved.

WHY? anything i did wrong in this code?

[ahmed yehia]

Static variables are not serialized.. In your example, since your are doing the serialization and deserialization using the same JVM instance, every object you create will refer to the same static member, hence changing one static member would change for all objects.

[adam Lui]

thanks
i was expecting a ZERO just like what a transient does

[Burkhard Hassel]

Howdy, ranchers!

adam Lui posted

i was expecting a ZERO just like what a transient does

No, serialization is for objects only. The static variables belong to the class - not to individual objects - so (de)serialization simply does not touch them at all.

There is no reason to assign any null (or 0) values to the static variables in the serialization process, because the static variables should only be accessed through the class identifier (e.g. SpecialSerial.z=42 in your case).

Yours,
Bu.
[ November 09, 2007: Message edited by: Burkhard Hassel ]