Java Serialization vs .NET Serialization - Java Perverse?

Tue, Aug 22, 2006 Did you know what happens in Java when you serialize a subclass of a non serializable class? I was surprised by the answer: it works!

Unfortunately it is not a good thing, because it will serialize fields from your subclass and no fields from the parent class. So you'll end up with a half serialized instance.

In .NET, it breaks at runtime, throwing an exception, which is I think, much more logical, because then you don't end up with half data somewhere.

Java Code:

import java.io.ByteArrayInputStream;
       import java.io.ByteArrayOutputStream;
       import java.io.ObjectInputStream;
       import java.io.ObjectOutputStream;
       import java.io.Serializable;
       
       
       
       public class Test
       {
         public static class Toto 
         {
           public String me;    
         }
         
         public static class Toto2 extends Toto implements Serializable
         {
           public String you;
           public String toString()
           {
             return me+" "+you;
           }
         }
         
         public static void main(String[] args) throws Exception
         {
           Toto2 t = new Toto2();
           t.me = "it's me";
           t.you = "it's you";
           System.out.println("t="+t);
           ByteArrayOutputStream b = new ByteArrayOutputStream();
           ObjectOutputStream oos = new ObjectOutputStream(b);
           oos.writeObject(t);
           ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(b.toByteArray()));
           System.out.println("u="+ois.readObject());
         }
       }

will output:
t=it's me it's you
u=null it's you

.NET Code:

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Xml;
using System.Xml.Serialization;
using System.Runtime.Serialization.Formatters.Binary;

namespace ConsoleApplication
{
    public class Toto
    {
        public string me;
        public override string ToString()
       {
            return me;
       }
    }

    [Serializable]
    public class Toto2 : Toto
    {
        public string you;
        public override string ToString()
       {
            return you + " " + me;
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            Toto2 t = new Toto2();
            t.me = "it's me";
            t.you = "it's you";
            using (FileStream fs = File.Create(@"c:\test.bin"))
           {
                BinaryFormatter bFormatter = new BinaryFormatter();
                bFormatter.Serialize(fs, t);
            }
            Console.WriteLine("t=" + t.ToString());
            Toto2u = null;
            using (FileStream fs = File.Open(@"c:\test.bin", FileMode.Open))
            {
                BinaryFormatter bFormatter = new BinaryFormatter();
                u = (Toto2)bFormatter.Deserialize(fs);
            }
            Console.WriteLine("u="+u.ToString());
            Console.ReadKey();
        }
    }
}

will throw an exception.

Java Serialization vs .NET Serialization - Java Perverse?

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