Graphical User Interfaces - Java - page 571

You can use the JOptionPane class in several other ways. For example, you can call its
showDialog() method with a list of strings; each is displayed on a push button in the dialog.
This method blocks until the user selects one of the buttons; the return value of the method is
an int telling which button the user clicked (it returns the array index of the string whose
button was pressed). Another method, showInputDialog() , lets you prompt the user for a
data value. Very, very convenient!
See Also
JDialog lets you write arbitrarily complicated dialogs. You subclass them in a manner simil-
ar to JFrame , specifying whether you want an application-modal or nonmodal dialog (a mod-
al dialog locks out the rest of the application, which is less convenient for the user but much
easier for the programmer). See Java Swing (O'Reilly) for information on JDialog .
Catching and Formatting GUI Exceptions
Problem
Your application code is throwing an exception, and you want to catch it, but the GUI runs in
a different Thread (see Chapter 22 ), so you can't.
Solution
Use setDefaultUncaughtExceptionHandler() .
Discussion
In days of yore, we had to use an unsupported feature for this! Now we use the Thread meth-
od setDefaultUncaughtExceptionHandler() , whose signature is:
public static void setDefaultUncaughtExceptionHandler(
Thread.UncaughtExceptionHandler handler);
The code in Example 14-6 shows a tiny demonstration of this technique.
Example 14-6. ThreadBasedCatcher.java