How do you repair an unhandled exception?

You can stop an unhandled exception by handling it. When your program crashes it will tell you exactly where it crashed and what exception it ran into. Dealing with the exception is the hard part. Generally, you want to take one of two approaches. The first is to make sure that the exception cannot happen. You may, for example, have to validate data to make sure that your users aren't allowed to give input which would result in a division-by-zero exception. The second is to allow the exception to be thrown, but use a try-catch block to catch it and print out a useful message instead of crashing. The method you choose will depend on what your program is supposed to do, who is using it, what exceptions are being thrown, where they're being thrown, etc. There's no silver bullet solution for handling an exception.