Re: Trying to save a Point2D.Double object

From:

Patricia Shanahan <pats@acm.org>

Newsgroups:

comp.lang.java.help

Date:

Sat, 16 Sep 2006 12:54:55 GMT

Message-ID:

<zuSOg.12359$bM.7734@newsread4.news.pas.earthlink.net>

e_matthes@hotmail.com wrote:

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).

....

class DoublePoint extends Point2D.Double implements Serializable {

    public DoublePoint() {
        super();
    }

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

}

Doesn't a serializable subsclass of a non-serializable class have to
handle serializing the superclass data explicitly?

Your program works if you add to the DoublePoint code:

   private void writeObject(java.io.ObjectOutputStream out)
   throws IOException{
     out.writeDouble(getX());
     out.writeDouble(getY());
   }
   private void readObject(java.io.ObjectInputStream in)
     throws IOException, ClassNotFoundException{
     double x = in.readDouble();
     double y = in.readDouble();
     setLocation(x,y);
   }

output:

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

Patricia