Trying to save a Point2D.Double object

Hello everyone,

I have an application which uses many Point2D.Double objects, and now
that I am trying to write code which saves objects from the
application, I discover the whole mess with Point2D.Double being not
serializable since 1999(!).

With a little research, I found what I thought was a workaround,
creating a custom, serializable class which extends Point2D.Double. It
is not working, though; when I save an object of the extended class, it
always reads back as (0.0, 0.0).

I have written a small program which creates one DoublePoint object,
saves it, changes it, reads it, and writes it. Note that if you run
this code, it will save a .dat file to your computer without checking
whether that file exists. I assume you do not have a file called
doublePointSaveTestFile.dat on your computer. :)

----- BEGIN CODE -----

import java.awt.geom.*;
import java.io.*;
import javax.swing.*;

public class DoublePointSaveTester {

    public DoublePointSaveTester() {

        DoublePoint pointToSave = new DoublePoint(1.2d, 0.3d);
        System.out.println("Initialized pointToSave: " + pointToSave);

        writeDoublePoint(pointToSave);

        pointToSave = new DoublePoint(6.66d, 6.666d);
        System.out.println("Changed pointToSave: " + pointToSave);

        pointToSave = readDoublePoint();

        System.out.println("Read pointToSave: " + pointToSave);

    }

    private void writeDoublePoint(DoublePoint pointIn) {
        try {
            FileOutputStream fileStream = new
FileOutputStream("doublePointSaveTestFile.dat");
            ObjectOutputStream objectStream = new
ObjectOutputStream(fileStream);
            objectStream.writeObject(pointIn);
            objectStream.close();
        } catch (IOException e) {
            JOptionPane.showMessageDialog( null, e.toString() );
        }
    }

    private DoublePoint readDoublePoint() {
        DoublePoint pointRead = null;
        try {
            FileInputStream fileStream = new
FileInputStream("doublePointSaveTestFile.dat");
            ObjectInputStream objectStream = new ObjectInputStream(fileStream);
            pointRead = (DoublePoint)objectStream.readObject();
            objectStream.close();
        } catch (IOException e) {
            JOptionPane.showMessageDialog( null, e.toString() );
        } catch (ClassNotFoundException e) {
            JOptionPane.showMessageDialog(null, "Error - Inappropriate file
type");
        }
        return pointRead;
    }

    public static void main(String arg[]) {
        DoublePointSaveTester saveTester = new DoublePointSaveTester();
    }

}

class DoublePoint extends Point2D.Double implements Serializable {

    public DoublePoint() {
        super();
    }

    public DoublePoint(double x, double y) {
        super(x, y);
    }

}

----- END CODE -----

Output:
Initialized pointToSave: Point2D.Double[1.2, 0.3]
Changed pointToSave: Point2D.Double[6.66, 6.666]
Read pointToSave: Point2D.Double[0.0, 0.0]