What is an Exception?

Why use exceptions instead of return values?

1. Forces error checking
2. Cleans up your code by separating the normal case from the exceptional case. (The code isn't littered with a lot of if-else blocks checking return values.)
3. Low overhead for non-exceptional case

Traditional programming languages set flags or return bad values like -1 to indicate problems. Programmers often don't check these values.

Java throws Exception objects to indicate a problem. These cannot be ignored.