Name: skT88420 Date: 04/16/99


In How to Make Dialogs in the Java Tutorial, counsel is given
about using a PropertyChangeListener to intercept JOptionPane
button presses. See page 7 of dialog.html. Sample source code
appears in CustomDialog.java. However, an important fact is
missing in the discussion. The example and source code show that
the dialog is setVisible (false) when exiting. If one then
reshows the same dialog instance with setVisible (true) and then
presses the same button again, a firePropertyChangeEvent () is
called just like before. But alas, the oldValue and newValue of
the property being changed are the same (because the user pressed
the *same* button), resulting in no property change event
actually being fired! So the user experience is that pressing the
OK button, for example, the first time works but does not work
when pressing it again if the dialog is brought back a second
time. Ouch!

Alternatively, if one does some kind of range checking when the
OK button is pressed, detects an error, puts up an error dialog,
and then allows the user to correct the error, then the OK button
no longer works. Ouch again!

I interpret this deplorable situation as a bug in JOptionPane.
Ideally, it *should* reset the property value to null somehow so
that subsequent presses of the same button will work.

You may see this as a programmer error. The simple workaround
described below works, but at the least should have been
documented in the Java Tutorial. I have sent a similar message
to the Java Tutorial authors.

Please note that because of the successful workaround provided,
I've listed the Impact on User, below, as "No Impact." It's still
a bug, at least in the Java Tutorial documentation if not in
the JOptionPane source code.

I've also listed the Symptoms as causing the program to hang
because that's what the user sees -- a dialog such that pressing
the Okay button doesn't go away and process anything.
(Review ID: 54563)
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