But as an author if there's something important You're still ignoring other people's point in this thread: you (the author of a library/package) cannot decide

But as an author if there's something important You're still ignoring other people's point in this thread: you (the author of a library/package) cannot decide what is important for the users of your library. You can guess, but your guess will always be wrong for a subset of your downstream users. And speaking from the other side, as an application developer: for most of my code, an ArrayIndexOutOfBoundsException is a pretty serious exception. How do I go about making it a checked exception?