Re: Help! Swing & Threads
blmblm@myrealbox.com wrote:
In article <447f42c7$0$2648$ed2619ec@ptn-nntp-reader01.plus.net>,
Thomas Hawtin <usenet@tackline.plus.com> wrote:
blmblm@myrealbox.com wrote:
In article <PPmdnaftaqUszePZRVn-hg@comcast.com>,
Eric Sosman <esosman@acm-dot-org.invalid> wrote:
JFileChooser doesn't block, or at any rate not for very
[...]
Well .... JFileChooser, as far as I can tell, isn't really itself
a GUI component, is it? The GUI components are the dialogs it pops
up, when showOpenDialog() or showSaveDialog() is called. And those
are modal dialogs, so they do indeed block any action on other GUI
components.
JFileChooser is a GUI component. It extends JComponent and it even has
L&F delegate thingy. It happens to have some convenience methods that
open it in a modal dialog box, for use if for some reason you don't
think modal interfaces are criminal.
You're so right, as I probably would have known if I'd read the
javadocs carefully rather than just grabbing the example ....
The API docs are quite difficult to read - millions of methods, and a
few of the useful. Particularly with Swing, the source code is very useful.
[ snip ]
Try this experiment: Write yourself a little GUI that fires
up *two* JFileChoosers simultaneously, and browse through a
couple different parts of your disk in side-by-side choosers.
The experiment itself won't teach you much, but pondering what's
going on might.
Below is my attempt to do -- well, something that's as close as
I can figure out to what you described. It doesn't behave as
you describe, though, since both the open dialogs are modal.
What am I doing differently from what you had in mind?
Don't use modal dialogs...
Ah. Got it. It would never have occurred to me to try this approach,
but of course if JFileChooser is a JComponent, why not. And then how
do you connect that to program actions .... Experiment suggests that
what one wants is an ActionListener. Okay.
Yes, but not the action listener also gets fired for cancel. You should
check to see whether the command is APPROVE_SELECTION or
CANCEL_SELECTION. Also of not is setFileSelectionMode which determines
how file vs directory selection operates.
I guess most of the applications I've used that employ a "file chooser"
do so in the context of a modal dialog box. The only exception I
can think of right now is something like a file browser, but I can
believe there are others.
If you want more control over the modal dialog, then you have to
reimplement showDialog yourself. Also rather than popping up millions of
dialogs it's often better to make your parent form slide open and the
file chooser appear without "moving to another room".
Thanks. (BTW, I think I prefer your approach of using fully-qualified
names in the code to my long bunch of "import" statements, for this
kind of example.)
I don't usually do it quite so much. If you are dealing with loads of
swing classes and little else, you might as well import the entire
javax.swing with import *. But I do like to see which packages classes
are from, particularly in example or unusual code when the reader is not
necessarily familiar with where everything has come from. And it's easy
to accidentally miss out import statements when copying and pasting.
Tom Hawtin
--
Unemployed English Java programmer
http://jroller.com/page/tackline/