How can I serialize static variables

It's going to be dangerous to serialize the static value along with individual instances... e.g

1. create 4 quiz objects (1,2,3,4) and serialize them, all storing next available id as 5

2. create 3 more quiz objects (5,6,7) so the next available id is 8

3. deserialize one of the initial objects and the next available id gets reset to 5

4. create new quiz object, id gets set to 5, even though another instance of quiz exists with that id -- Ooops

Have included code here for how to do it just in case you can ensure that the above scenario cannot arise or be a problem

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.IOException;

import java.io.ObjectInputStream;

import java.io.ObjectOutputStream;

import java.io.Serializable;

public class ForumQuestion {

public static void main( String[] args ) throws IOException, ClassNotFoundException {

ByteArrayOutputStream os = new ByteArrayOutputStream();

ObjectOutputStream out = new ObjectOutputStream( os );

Quiz q = null;

for( int i = 0; i < 4; i++ ) {

q = new Quiz();

}

out.writeObject( q );

out.close();

for( int i = 0; i < 3; i++ ) {

new Quiz();

}

ByteArrayInputStream is = new ByteArrayInputStream( os.toByteArray() );

ObjectInputStream in = new ObjectInputStream( is );

in.readObject();

new Quiz();

}

}

class Quiz implements Serializable {

private static volatile int nextId = 1;

private int myId;

public Quiz() {

myId = nextId++;

System.out.printf( "Created quiz %d%n", myId );

}

private void writeObject( ObjectOutputStream os ) throws IOException {

os.defaultWriteObject();

os.writeInt( nextId );

System.out.printf( "Stored quiz %d, nextId %d%n", myId, nextId );

}

private void readObject( ObjectInputStream is ) throws IOException, ClassNotFoundException {

is.defaultReadObject();

nextId = is.readInt();

System.out.printf( "Restored quiz %d, nextId %d%n", myId, nextId );

}

}

The Quiz class shows how to serialize the static field along with the instance, but the output illustrates the danger:

Created quiz 1

Created quiz 2

Created quiz 3

Created quiz 4

Stored quiz 4, nextId 5

Created quiz 5

Created quiz 6

Created quiz 7

Restored quiz 4, nextId 5

Created quiz 5

sorabaina at 2007-7-13 10:05:52 >