I'd like to use to a custom exception to have a user-friendly message come up when an exception of any sort takes place.
What's a good straightforward way of doing this? Are there any extra precautions I should take to avoid interfering with Swing's EDT?
Exception Translation:
It's a good idea to not pollute your application with messages that have no meaning to the end user, but instead create meaningful Exceptions and messages that will translate the exception/error that happened somewhere deep in the implementation of your app.
As per @Romain's comment, you can use Exception(Throwable cause) constructor to keep track of the lower level exception.
From Effective Java 2nd Edition, Item 61:
[...] higher layers should catch lower-level exceptions and, in their place, throw exceptions that can be explained in terms of the higher-level abstraction. This idiom is known as exception translation:
// Exception Translation try { // Use lower-level abstraction to do our bidding ... } catch(LowerLevelException e) { throw new HigherLevelException(...); } 
You can use java.lang.Thread.UncaughtExceptionHandler which catches all exceptions you haven't cared for yourself
import java.lang.Thread.UncaughtExceptionHandler; public class MyUncaughtExceptionHandler implements UncaughtExceptionHandler { public void uncaughtException(Thread t, Throwable e) { Frame.showError("Titel", "Description", e, Level.WARNING); e.printStackTrace(); } } register it in your app:
public static void main(String[] args) { Thread.setDefaultUncaughtExceptionHandler(new MyUncaughtExceptionHandler()); } and in your GUI you can use org.jdesktop.swingx.JXErrorPane from SwingX to show a nice error popup, which informs the user about exceptions.
public static void showError(String title, String desc, Throwable e, Level level) { JXErrorPane.showDialog(this, new ErrorInfo(title, desc, null, null, e, level, null)); } 