Serialization

package wdf;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.ObjectInputValidation;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamException;
import java.io.Serializable;

class Base implements Serializable {

}

class Sub extends Base {
    private Sub() {}
    public Sub(int g) {}

    int q = 9;
}

class Ser extends Sub implements Serializable, ObjectInputValidation {
    Ser() { super(7); }

       private void writeObject(java.io.ObjectOutputStream out) throws IOException {
            System.out.println("writeObject");
            out.defaultWriteObject();
        }

       private Object writeReplace()  {
            System.out.println("writeReplace");
            return this;
        }

    int a = 8;
    float f = 9f;
    String s = "823982";

       private Object readResolve() throws ObjectStreamException {
            System.out.println("readResolve");
            return this;
        }

       private void readObject(java.io.ObjectInputStream in) throws IOException, ClassNotFoundException {
            System.out.println("readObject");
            in.registerValidation(this, 10);
            in.defaultReadObject();
        }


    public void validateObject() throws InvalidObjectException {
        System.out.println("jjj");
//      if (a != 9) {
//
//          throw new InvalidObjectException("a != 9");
//      }

    }


}

public class My {



    public static void main(String[] args) {
        String fileName = "d:\\del.me";
        int bufSz = 8 * 1024;
        Ser obj = new Ser();

        try {
            ObjectOutputStream oos = new ObjectOutputStream(
                    new BufferedOutputStream(new FileOutputStream(fileName), bufSz));
            oos.writeObject(obj);
//          oos.close();
            oos.flush();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        Ser obj1 = null;
        Ser obj2 = null;
        try {
            ObjectInputStream ois = new ObjectInputStream(
                    new BufferedInputStream(new FileInputStream(fileName), bufSz));

            ObjectInputStream ois1 = new ObjectInputStream(
                    new BufferedInputStream(new FileInputStream(fileName), bufSz));

            obj1 = (Ser) ois.readObject();
            obj2 = (Ser) ois1.readObject();
        } catch (IOException | ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        System.out.println(obj1.a);
        System.out.println(obj2.a);

    }

}