I am not particularly a fan of JCS (Jakarta Cache System) as I find ehcache code very clean and simple. But I have to say the author has some good comments on the site:
Nulls vs. ErrorsI started to support
ObjectNotFoundExceptionsfor failed gets but the overhead and cumbersome coding needed to surround a simple get method is ridiculous. Instead the JCS return null.
For having seen too many times the ObjectNotFoundException "pattern", I can only agree!