Re: Longevity of static class variables in Applet JVM

From:

Mark Space <markspace@sbc.global.net>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 05 May 2009 18:57:40 -0700

Message-ID:

<z86Ml.32662$ZP4.26584@nlpi067.nbdc.sbc.com>

Richard Maher wrote:

Are static class variables once referenced in an Applet ever candidates for
garbage-collection in a JVM, specifically when there are no longer any
active Applets currently referencing them? (That is, the page that loaded

Yes, all objects, including static ones and classes, are available for
garbages collection once they are no longer referenced.

How exactly a browser handles this, I have no idea.

If events are then delivered on such static objects (once again, sometime
after the last Applet/ web-page to have referenced them has long gone) what
thread is the event delivered in? (I'm guessing the standard browser EDT but
the Java 6 reorg with Applet threads has me doubting it)

You have to be holding a refernce to a class to get events related to
it, so in that case it couldn't be garbage collected. Also, Swing and
AWT don't deliver any sort of GC events, ever. You're pretty confused.

You might be able to get some info by keeping phantom references to
objects around. The queue associated with the phantom reference will
receive events when the object is gc'd.

It might be even easier however to just connect a debugger or profiler,
and observe which objects are gc'd and when.