The core of AI is really graph search. A lot of intelligent behavior can essentially be boiled down to searching through a decision tree for the most effective solution (it gets more complicated if an opponent is involved). So, I'd suggest learning pathfinding/search first (depth-first, breadth-first searches, uniform cost search, and then more informed searches and in particular A*, which is invaluable and has a lot of very good resources (some of which should be linked to at the bottom of that wikipedia page)).
Really, though, your university should have a course on AI. At third year, it should also be accessible (though I'm sure some topics wait until fourth year). School is as good a place to start learning something as any, and worse than others.
As for programming languages, I've heard it said that Prolog is good for this sort of thing, and seen it used in AI courses and so on. It's certainly not necessary (at all) for understanding how to do pathfinding and various other subjects in AI. You can use Java for these, or even C (it wouldn't be all that pleasant, but it's done all the time). Or you could take the opportunity to learn whatever language is the focus of whatever guide you use to learn various subjects in AI (e.g. Prolog or Python may be used).