tl;dr: Check this out, might be fun: http://codegolf.stackexchange.com/questions/47125/water-balloon-wars
It’s a little mini programming competition on Stack Overflow’s Code Golf site. Usually these competitions are a bit esoteric (make a program that does XYZ in as few characters as possible) and not very friendly, but this one is specifically for Java. The goal is to create an AI player that participates in a bit of a “hot potato” game.
Definitely might be worth checking out, if you’re into this sort of thing.