Language Processing

So I am writing a Java program that needs some language parsing. This language parsing is meant to be extended and modified in the near future. The thing is, i already know how to flex/bison this shit, but I think that flex and bison are shit, so I don't want to use them. Alternatives?

tl/dr: flex and bison are shit, what can i use instead?

>>6
It's an input system for an experimental logic framework. I need it for getting the conditions of reasoning for the system, and hand-coded is not an option for my boss because it is not ENTERPRISE enough.