Serialization Question

[geeta vemula]

source: http://www.examulator.com/phezam/showquestion.php

import java.io.*;

public class Serialize1{
public static void main(String argv[]) throws IOException{
Serialize1 o = new Serialize1();
o.go();
}
public void go() throws IOException{
String[] obs = {"one","two","three"};
FileOutputStream out = new FileOutputStream("mystrings.ob");
ObjectOutputStream s = new ObjectOutputStream(out);
s.writeObject(obs);
s.flush();
}

}

Answer is : Compilation and output of the serialized content of the obs String array to a new file called mystrings.ob

My Doubt is why it is not raising any exception or giving any error when the class is not implementing Serialize interface?

Thanks,
Geeta Vemula

[Harvinder Thakur]

Geeta, you are serializing object obs which is an array of Strings and not Object ob which is an instance of Serialize1

 String[] obs = {"one","two","three"};
 .....
 s.writeObject(obs);//serializing obs above

and since String class implements Serializable interface the answer is correct.

[geeta vemula]

Then does arrays implement serializable interface by default?
I am not clear with this.

Thanks,
geeta Vemula

[Harvinder Thakur]

It has got nothing to do with array being serializable or not. An array of a class is serializable if all the contents of the array are serailizable objects.

When i say String imlements serializable then i am referring to the contents of the String array. All the objects in the array are Strings and String implements serializable.

Look at the following code. Even though Object class does not implement serializable i am still able to serialize an Object array containing all String objects which are serializable.

import java.io.*;
 
public class Tester {
public static void main(String argv[]) throws IOException,  
                                               ClassNotFoundException 
        {
Tester o = new Tester();
o.go();
}
 
     public void go() throws IOException, ClassNotFoundException {
//String[] obs = { "one", "two", "three" };
Object[] obs = { "one", "two", "three",};
//Object[] obs = { "one", "two", "three", new Object() }; //LINE 1

FileOutputStream out = new FileOutputStream("d:\\mystrings.ob");
ObjectOutputStream s = new ObjectOutputStream(out);
s.writeObject(obs);
s.flush();

FileInputStream in = new FileInputStream("d:\\mystrings.ob");
ObjectInputStream ois = new ObjectInputStream(in);
Object[] abc = (Object[])ois.readObject();

System.out.println("abc[0]: "+abc[0]);
System.out.println("abc[1]: "+abc[1]);
System.out.println("abc[2]: "+abc[2]);
      }
}

Hope this clears your doubt.