In all our Java 1.4 apps on Mac, we have a minor bug when it comes to
shutting down.
We've registered a com.apple.eawt.ApplicationListener to know when the
user tries to quit the program from the application menu, or by other
OS-specific means. (For example, right-clicking the app's icon in the
dock and selecting 'Quit', or by logging out or shutting down.)
We need to prompt the user to save/discard all their changes when they
try to close the program. We do this in a separate thread, so the AWT
thread is free for progress dialogs and question dialogs. (Technically
if we made every dialog a modal dialog this might solve our problem,
but we found that's very dangerous; two stacked modal dialogs is bad
news in Java. For example: if an error occurs while saving, then
juggling the modal dialogs safely is a real pain.)
The bug is this: in our current implementation, we correctly close the
application when requested, but if the quit is a result of the user's
attempt to log off/shutdown/restart, then we're always told "The
application X has cancelled shutdown/restart/etc."
We can fix this by changing our code to the following:
public void handleQuit(ApplicationEvent e) {
...
windowClosingThread.start();
e.setHandled(true);
}
But then once the true flag gets set, the program immediately closes...
the users work isn't saved.
So instead we say:
public void handleQuit(final ApplicationEvent e) {
...
windowClosingThread.start();
}
And inside the extra thread, we eventually say "e.setHandled(true)"
when all the user's work is safe. (This is the current implementation
that stops the user from logging out.)
From our primitive dabbling, it looks like we have 2 options:
1. Stop the user from logging out
2. Discarding all their changes
Has anyone experienced this before? If so, how did you approach it?
(This is not a problem in the one app we still use Java 1.3 for... but
the listener is completely different in 1.3.)
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