Re: Accessing Preferences from ShutdownHook?
Peter Duniho wrote:
On Mon, 04 Feb 2008 19:20:58 -0800, Knute Johnson
<nospam@rabbitbrush.frazmtn.com> wrote:
[...]
I think given the problem you are having that I wouldn't try to update
my Preferences in a shutdown hook, but instead do it earlier, either
when the state changes that you want to keep or before the actual
shutdown starts such as in a WindowListener.
I could do the former, though it seems wasteful. Because of that I'd
prefer to leave it until shutdown.
How wasteful? I think that you might be falling into the pitfall of
premature optimization. Unless you change the preferences thousands of
times a second, I wouldn't bother. I think its pretty typical to update
the preferences as the user makes there changes.
As far as the latter goes, I can't do that because the run-time can be
shut down without actually closing my window. I did try a listener to
respond to the closing event, and never received it in shutdown
scenarios that don't actually involve closing the window (e.g. on the
Mac, using the "Quit" menu item provided by the run-time).
Not to mention that a JVM could actually die without running the
shutdown hooks at all.
So, I infer from your reply that you feel it would actually be unsafe to
use the Preferences class in a shutdown hook, even calling
Preferences.flush()? Indeed, this was my concern, and it sounds like
you are confirming it (or at least are agreeing that I should be worried
:) ).
I looked at the WindowsPreferences version, and it doesn't use shutdown
hooks. That doesn't mean anything about the OSX version though.
I really think that you should make the changes when the state changes.
Leave the caching and flushing to the Preference class. If you find
performance problems, *then* you can optimize (with aid from a profiler
ofcourse).
--
Daniel Pitts' Tech Blog: <http://virtualinfinity.net/wordpress/>