.FULL PRODUCT VERSION :
java version "1.5.0_04"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0
Java HotSpot(TM) Client VM (build 1.5.0_04-b05, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Windows XP Professional

A DESCRIPTION OF THE PROBLEM :

When an Object is written to an ObjectOutputStream and the flush method is called, not all the object attributes (I have spotted a Map) are written to the stream, where as Imuttable Objects such as String are. Flush should flush all objects linked to this object.

I realise handles are kept in a map, this is OK, but the object in the stream should be written


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Use the code I provide, and run

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Cat before write:Name: Anthony has: all parts intact
Cat after write:Name: Anthony written has: all parts intact
Cat after read:Name: Anthony has: is not complete
ACTUAL -
Cat before write:Name: Anthony has: all parts intact
Cat after write:Name: Anthony written has: all parts intact
Cat after read:Name: Anthony has: all parts intact

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
//Separate callses into separate files
//Cat.java

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.HashMap;
import java.util.Map;

public class Cat extends Animal{
private static final long serialVersionUID = 1L;
private Map attributes = new HashMap();

public void setAttributes(){
setName("Anthony");
attributes.put(new Integer(0), "Right Back Leg");
attributes.put(new Integer(1), "Right Front Leg");
attributes.put(new Integer(2), "Left Back Leg");
attributes.put(new Integer(3), "Left Front Leg");
}

public Map getAttributes() {
return attributes;
}

public String toString(){
String retVal = "Name: " + getName() + " has: ";
if(attributes.size() == 4){
retVal += " all parts intact";
}else{
retVal += " is not complete";
}
return retVal;
}

public static void main(String [] args){
File serFile = null;
try {
Cat item = new Cat();
item.setName("Anthony");
item.setAttributes();
item.setTranform(new CatTransform());

System.out.println("Cat before write:" + item);

serFile = File.createTempFile("cat", "ser");
FileOutputStream fos = new FileOutputStream(serFile);
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(item);
oos.close();
fos.close();

System.out.println("Cat after write:" + item);

//
// deserialize
//

ObjectInputStream ois = new ObjectInputStream(new FileInputStream(serFile));
Cat itemread = (Cat) ois.readObject();
ois.close();
serFile.delete();

System.out.println("Cat after read:" + itemread);

}catch(Exception exp){
exp.printStackTrace();
}
}
}

// Animal.java

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

abstract class Animal implements Serializable{

/**
*
*/
private String name;
private transient Transform tranform;
private static final long serialVersionUID = 1L;


private void writeObject(ObjectOutputStream out)
throws IOException, ClassCastException {

Transform inverse = null;
if(tranform != null)inverse = tranform.transform(this);

out.defaultWriteObject();
out.flush();

if(inverse != null)inverse.transform(this);
this.setName(this.getName() + " written");

}

private void readObject(ObjectInputStream in)
throws IOException, ClassNotFoundException {
in.defaultReadObject();
}

public void setTranform(Transform t){
this.tranform = t;
}

/**
* @return Returns the name.
*/
public String getName() {
return name;
}

/**
* @param name The name to set.
*/
public void setName(String name) {
this.name = name;
}

}

//Transform.java

abstract class Transform{
abstract Transform transform(Animal a);
}

// CatTransform.java

import java.util.HashMap;
import java.util.Map;

class CatTransform extends Transform{
Transform transform(Animal a){
Cat cat = (Cat) a; // I can do this because I know the transform is used on Object of type Cat
Map removed = new HashMap(cat.getAttributes());
cat.getAttributes().clear(); //chop off all the cats legs
return new InverseCatTransform(this,removed);
}


public static class InverseCatTransform extends Transform{
private CatTransform inverse;
private Map missing;

public InverseCatTransform(CatTransform transform, Map removed) {
inverse = transform;
missing = removed;
}

Transform transform(Animal a){
Cat cat = (Cat) a; // I can do this because I know the transform is used on Object of type Cat
cat.getAttributes().putAll(missing);
return inverse;
}
}
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Implement Write replace in Animal instead, and clone the animal, then chop off the clones legs and return the dismembered clone.

However this has performance implications as if I am sending say, 100 cats, and they all have the same mask, then I expect that my mask will only be written once to the stream. However with the clone I now have the overhead of 100 masks.

The above example is a falacy, I am developing a dynamic transiencience of large objects. Our customer object may have thousands of attributes, I was to get back the customers names say I dont need the other 500 attributes so I create a transform and include it in the request, this then lops off the unessesary items...