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From: Lothar Kimmeringer <news200709@kimmeringer.de>
Newsgroups: comp.lang.java.programmer
Subject: Re: File object and serialization - information is lost
Date: Wed, 8 Jun 2011 20:18:36 +0200
Organization: Organization?! Only chaos here!
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Sebastian wrote:

> I seem to misunderstand a thing about java.io.File. I wanted to use
> the File object to transport information files existing in one place
> (basically, a directory listing) to another place.
> 
> The API says File serves as an abstract representation of a file, and
> that it implements Serializable.

That should say it all. It only represents a file, but nothing more.

> However, after Serialization/Deserialization (in another JVM) the
> methods lastModified() and length() return 0. This is not what I
> expected.

Have a look into the source of java.io.File. The only member are
(copied from JDK 1.6.0):

    /**
     * This abstract pathname's normalized pathname string.  A normalized
     * pathname string uses the default name-separator character and does not
     * contain any duplicate or redundant separators.
     *
     * @serial
     */
    private String path;

    /**
     * The length of this abstract pathname's prefix, or zero if it has no
     * prefix.
     */
    private transient int prefixLength;

Only one value being serialized, the path. This doesn't come as
a surprise since it's only representing a file in an abstract
way and that's the path (including the filename).

> Is there a standard object to transport this information, or do I have
> to define my own?

When I was in need for something like this (for a GWT-application)
I implemented it myself because it was faster than searching the
Internet for something that contains all I need.


Regards, Lothar
-- 
Lothar Kimmeringer                E-Mail: spamfang@kimmeringer.de
               PGP-encrypted mails preferred (Key-ID: 0x8BC3CD81)

Always remember: The answer is forty-two, there can only be wrong
                 questions!