Re: Singletons?

From:

Mark Space <markspace@sbcglobal.net>

Newsgroups:

comp.lang.java.help

Date:

Tue, 13 Jun 2006 19:52:30 GMT

Message-ID:

<2IEjg.147345$F_3.125347@newssvr29.news.prodigy.net>

Ian Shef wrote:

I don't know the answer to your questions, but you can sidestep the questions
by defining a no-argument constructor and giving it the "private" keyword.
This way, there is no way that this class can be instantiated unless one of
its own static methods does the deed. [Well, maybe there is a cheat via
reflection.]

Your questions are still valid, and I am interested in the answers myself.

I'd thought of that myself. However, a quick web search yielded this:

http://www.javacoffeebreak.com/articles/designpatterns/index.html

The article points out that there's a race condition in the general case
of a Java singleton object. The factory method which creates a
singleton should be synchronized. Obvious once someone points it out,
but still it's a good case right there for design patterns, not to
mention web searches. ;)

I also did a web search for "java object memory footprint" which yeiled
some interesting stuff. However, Oliver may have more recent and
up-to-date reference there. (I haven't looked at it yet, still pouring
over what I've got now.)

http://www.javaworld.com/javaworld/javatips/jw-javatip130-p3.html

This says 8 bytes is the minimum Java will allocate, and a lot more for
strings. Check Oliver's post before believing this though.