Re: updating an ImageIcon's backing BufferedImage content from multiple threads

Lew <>
Sun, 05 Apr 2009 19:48:34 -0400
Knute Johnson wrote:


Think of all the cases where you draw something to a BufferedImage in
one thread and then call repaint(). I've never seen a problem with
that. There may very well be some synchronization in the queue between
the call to repaint() and the calls to paintComponent() et al however.

I thought the drawing of the BufferedImage always happened on the EDT. I
don't know of such cases as you describe.

On the other hand, I've never seen a case where a change was not visible
from one thread to another. I know that there is no guarantee that it

Again I ask, on a multi-processor machine?

will be so but I have never seen a case of it with Sun's JVM. It is not
required to be invisible, it just may be. I would really like to be
able to create a program that could demonstrate a lack of visibility
across threads.

In any case the OPs problem is easily solved by synchronizing access to
the data.

AIUI, the advice "do all GUI work on the EDT" applies to drawing
BufferedImages, too.


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