Thread: Sub class Serialization

Hi All,

I am new to this community, First of all I would like to say Hellooooooo to every body. Now lets get back to the business .

So my First question is around the Serialization. Let's say there is Class B which is a Sub Class of A, Now if A does not implements Serializable interface and B does, So will I be able to Serialize B ?

Hi Param,

Welcome to the forum.

Back to youre question: ofcourse, B extends A, wich means also the interface.

Originally Posted by Bryan

Hi Param,

Welcome to the forum.

Back to youre question: ofcourse, B extends A, wich means also the interface.

Thanks for your reply Bryan..

I will really appriciate if could you please explain...

Originally Posted by helloworld922

Interfaces get inherited, but they do not propagate upwards.

So, in this case A is not serializable, but B is.

If you were to declare A to implement Serializable, B would automatically inherit this trait from A and also be Serializable.

Hey HelloWorld thank you for jumping in...

So you mean to say that( correct me If I am wrong somewhere) in my case if class A has attribute say 'age'
And class B has attribute say 'name' and now when I will Serilize the object of B


1. I m not going to receive any type of compile or runtime error.
2.Only the value of 'name' attribute of Class B will be stored , and the value of 'age'(Attribute of A class) will not be stored.

Please confirm...

Originally Posted by helloworld922

edit:

hmm.. never mind. I did some actual testing and I guess that in order to be Serializable, a class and all of it's super classes must be Serializable (except for Object, which can be written out no problem).

However, declaring A to be Serializable as mentioned before does allow B to be Serializable (again, it's important to make sure that all members of B are Serializable).

You can of course write your own custom serialization/deserialization code, but I think the checking for Serializable is done before the over-written methods can be called.

yeah, I did a small practical of serialization and found that attribute belongs to A(in our case age) will not be stored(Serillized) as A does not implements Serilizable interface but fileds of B will be.

Here I am sending you the code...

public class SerilizationExample {
public static void main(String [] args)
{
Employee e = new Employee();
e.setAge(24);
//e.age = 100;
e.name = "Param.....";
e.address = "Mumbai, India....";
e.SSN = 11122333;
e.number = 101;
try
{
FileOutputStream fileOut =
new FileOutputStream("employee.ser");
ObjectOutputStream out =
new ObjectOutputStream(fileOut);
out.writeObject(e);
out.close();
fileOut.close();
}catch(IOException i)
{
i.printStackTrace();
}
}

}

class Human
{
public int age;
public int getAge() {
return age;
}

public void setAge(int age) {
this.age = age;
}
}

class Employee extends Human implements java.io.Serializable
{
public String name;
public String address;
public transient int SSN;
public int number;
public void mailCheck()
{
System.out.println("Mailing a check to " + name
+ " " + address);
}
}

class DeserializeDemo
{
public static void main(String [] args)
{
Employee e = null;
try
{
FileInputStream fileIn =
new FileInputStream("employee.ser");
ObjectInputStream in = new ObjectInputStream(fileIn);
e = (Employee) in.readObject();
in.close();
fileIn.close();
}catch(IOException i)
{
i.printStackTrace();
return;
}catch(ClassNotFoundException c)
{
System.out.println("Employee class not found");
c.printStackTrace();
return;
}
System.out.println("Deserialized Employee...");
System.out.println("Name: " + e.name);
System.out.println("Age: " + e.getAge());
System.out.println("Address: " + e.address);
System.out.println("SSN: " + e.SSN);
System.out.println("Number: " + e.number);
e.mailCheck();
}
}