ObjectInputStream returns a wrong boolean value of a object

Question

ObjectOutputStream.writeObject once, then change the boolean value of the Contact object, ObjectOutputStream.writeObject again, but when ObjectInputStream.readObject, it returns SAME boolean values which should be different. can somebody explain me this? please. thx
   1. import java.io.*; 
   2. import java.util.*; 
   3.  
   4. public class TestSerializable { 
   5.      
   6.     /** Creates a new instance of TestSerializable */ 
   7.     public static void main(String args[]){ 
   8.         new TestSerializable(); 
   9.     } 
  10.      
  11.     public TestSerializable() { 
  12.         try{ 
  13.             Contact contact = new Contact("email","group",1); // contact.isOnline = true for default; 
  14.              
  15.             FileOutputStream fos = new FileOutputStream("ser"); 
  16.             ObjectOutputStream oos = new ObjectOutputStream(fos); 
  17.  
  18.             oos.writeObject(contact); 
  19.              
  20.             contact.setOnline(false); 
  21.             oos.writeObject(contact); 
  22.  
  23.             oos.flush(); 
  24.  
  25.              
  26.             FileInputStream fis = new FileInputStream("ser"); 
  27.             ObjectInputStream ois = new ObjectInputStream(fis); 
  28.             Contact ccRead1 = (Contact)ois.readObject(); 
  29.             Contact ccRead2 = (Contact)ois.readObject(); 
  30.              
  31.             System.out.println("ccRead1.isOnline() = "+ccRead1.isOnline()); 
[u]  32.             System.out.println("ccRead2.isOnline() = "+ccRead2.isOnline() + " which should be FALSE. ERROR");  [/u]
  33.                        
  34.             oos.close(); 
  35.             ois.close(); 
  36.              
  37.         } 
  38.         catch(Exception e){ 
  39.             e.printStackTrace(); 
  40.         } 
  41.          
  42.     } 
  43.      
  44. } 
  45.  
  46.  
  47.  
  48.  
  49.  
  50. import javax.swing.tree.DefaultMutableTreeNode; 
  51. import javax.swing.tree.*; 
  52. import java.util.*; 
  53.  
  54. public class Contact extends DefaultMutableTreeNode { 
  55.      
  56.     private String email; 
  57.     private int arrayIndex; 
  58.     private String group; 
  59.     private boolean online; 
  60.      
  61.   
  62.     public Contact(String email,String group,int arrayIndex, boolean online){ 
  63.         this.email = email; 
  64.         this.group = group; 
  65.         this.setArrayIndex(arrayIndex); 
  66.         this.setOnline(online); 
  67.         this.setUserObject(this); 
  68.         this.setAllowsChildren(false);         
  69.     } 
  70.      
  71.     public Contact(String email, String group){ 
  72.         this(email,group,-1,false); 
  73.     } 
  74.      
  75.     public Contact(String email, String group, int arrayIndex){ 
  76.         this(email,group,arrayIndex,true); 
  77.     } 
  78.      
  79.  
  80.      
  81.     public String toString(){ 
  82.         return this.email; 
  83.     } 
  84.  
  85.     public String getEmail() { 
  86.         return email; 
  87.     } 
  88.  
  89.     public int getArrayIndex() { 
  90.         return arrayIndex; 
  91.     } 
  92.  
  93.     public String getGroup() { 
  94.         return group; 
  95.     } 
  96.  
  97.     public boolean isOnline() { 
  98.         return online; 
  99.     } 
100.  
101.     public void setOnline(boolean online) { 
102.         this.online = online; 
103.     } 
104.  
105.     public void setArrayIndex(int arrayIndex) { 
106.         this.arrayIndex = arrayIndex; 
107.     } 
108.  
109.      
110. } 

Answer 1

Did you try the reset() technique again?
You could also have a look at ObjectOutputStream.writeUnshared().
And it's not returning a 'wrong value', it is conserving the object graph of the original object sent, which is what it's specified to do and what it's supposed to do. If you don't want that behaviour use reset() or writeUnshared().