basic concepts on Serialization

[Mark Tigerwood]

Hi all,

I would like to know some basic concepts on Serialization, Transient and Volatile? Any good java tutoiral explaining this with some good examples?

[Ankur Sharma]

Originally posted by Mark Tigerwood:
Hi all,

I would like to know some basic concepts on Serialization, Transient and Volatile? Any good java tutoiral explaining this with some good examples?

Dear Mark,

You must check this out....

You will definately find so much of you needed..

1. Most Important

another one is
Transient Variables

Hope it helps you out..

[Jesper de Jong]

Use Google!

When you search for "java serialization tutorial" you'll get a whole list of useful links in a fraction of a second.

[Mark Tigerwood]

Me too know there is a google engine which will bring us what we needed in a fraction of seconds. Why I am posting is, since this gorup members will know some good tutoirals(with samples/examples) for beginners than the google which will list from advanced. May be a silly question to post, but the below thing managed to post me..

 [B]No question too simple or small . . . [/B]  

Any way, thanks for your help. And here goes my second question on serializing/deserializing.

I am first serializied the object state in the file called "hi.ser", then when I tried to desrialized I am getting this error:

D:\SNA\Lea>java BoxRecover
java.io.InvalidClassException: Box; local class incompatible: stream classdesc s
erialVersionUID = -3683070876227151568, local class serialVersionUID = 425784837
1866910285
        at java.io.ObjectStreamClass.initNonProxy(ObjectStreamClass.java:463)
        at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:152
1)
        at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1435)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1
626)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1274)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java:324)
        at BoxRecover.main(BoxRecover.java:10)

import java.io.*;
 
public class Box implements Serializable{
 private int width;
 private int height;
 String boxname;
 int boxid;
 
 public void setWidth(int w){
  width = w;
 }
 
 public void setHeight(int h){
  height = h;
 }
 
 public void setBoxname(String name){
  boxname = name;
 }
 
 public void setBoxid(int id){
  boxid = id;
 }
 

 public int getWidth(){
  return width;
 }
 
 public int getHeight(){
  return height;
 }
 
 public String getBoxname(){
  return boxname;
 }
 
 public int getBoxid(){
  return boxid;
 }
 

 
 public static void main(String args[]){
  Box myBox = new Box();
 
  myBox.setWidth(50);
  myBox.setHeight(20);
  myBox.setBoxname("Test");
  myBox.setBoxid(20);
 
  try{
   FileOutputStream fs = new FileOutputStream("Hi.ser");
   ObjectOutputStream os = new ObjectOutputStream(fs);
   os.writeObject(myBox);
   os.close();
  }catch(Exception e){
   e.printStackTrace();
  }
 }
 
}
 

import java.io.*;

public class BoxRecover{
public static void main(String args[]){

Box myBox = new Box();
try{
FileInputStream fi = new FileInputStream("Hi.ser");
ObjectInputStream oi = new ObjectInputStream(fi);
Box width1 = (Box) oi.readObject();
System.out.println("width ::::::::"+myBox.getWidth());

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

[sven studde]

An InvalidClassException will be thrown when you change something in your Box class after writing to the file. I have no problems with the files you posted: I can compile and run them and get the expected output.

By the way, for testing purposes you can organize your classes like this:

import java.io.*;
 
class MyBox implements Serializable //Don't use the public modifier
{

}
 
public class SerializeDemo  //Save file using this name and compile/run using this name
{
public static void main(String[] args)
{
 //write objects then close file

//read objects and display them
}
}

[ November 11, 2006: Message edited by: sven studde ]
[ November 11, 2006: Message edited by: sven studde ]