import java.io.*;

public class Box implements Serializable{

    private int width;

    private int height;

    public void setWidth(int w){

        width = w;

    }

    public void setHeight(int h){

        height = h;

    }

    public int getWidth(){

        return width;

    }

    public int getHeight(){

        return height;

    }

    public static void main(String[] args){

        Box myBox = new Box();

        myBox.setWidth(20);

        myBox.setHeight(100);

        try {

            FileOutputStream fs = new FileOutputStream("foo.ser");

            ObjectOutputStream os = new ObjectOutputStream(fs);

            os.writeObject(myBox);

            os.close();

        } catch (Exception ex){

            ex.printStackTrace();

        }

        myBox = null;

        try{

            FileInputStream fis = new FileInputStream("foo.ser");

            ObjectInputStream is = new ObjectInputStream(fis);

            Box readBox = (Box) is.readObject();

            System.out.println("Box Obj width:" + readBox.getWidth());

            System.out.println("Box Obj height:" + readBox.getHeight());

        }catch (Exception ex){

            ex.printStackTrace();

        }

    }

}

Box Obj width:20

Box Obj height:100