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Thread: Sub class Serialization

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    Question 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 ?


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    Default Re: Sub class Serialization

    Hi Param,

    Welcome to the forum.

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

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    Default Re: Sub class Serialization

    Quote Originally Posted by Bryan View Post
    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...

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    Default Re: Sub class Serialization

    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.

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    Exclamation Re: Sub class Serialization

    Quote Originally Posted by helloworld922 View Post
    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...

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    Default Re: Sub class Serialization

    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.
    Last edited by helloworld922; April 23rd, 2010 at 01:28 AM.

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    Default Re: Sub class Serialization

    Quote Originally Posted by helloworld922 View Post
    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();
    }
    }

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