I wrote something like this in another language a few years ago. (not
JAVA) I rewrote the ELIZA program to handle the conversational part and
included a section which parsed incoming text against the contents of a
database. This allowed it to "learn" and reply with facts when it
recognised something it "knew". I called the thing "Plato", the host
name of my computer at the time.

Teaching was accomplished as part of the conversation stream with the
construct: "Tell Plato that X is Y". Plato would reply with "I now
believe X is Y".

If Plato noticed X mentioned in a conversation from then on it would
state that "X is Y".

I connected the input stream to a CGI web page allowing people on the
net to "converse" with Plato, but it could have been connected to any
chat stream.

Good luck, I had great fun with Plato in the "lite" language of MSQL.
JAVA is far more versatile so you should have even more fun.

I've written chatterbots in both Java and Prolog. For Java based efforts, I'd
suggest you take a look at AliceBot <http://www.alicebot.org/>

Specifically, there are a bunch of Java chatterbots that make use of the AIML
markup language available for download at <http://www.alicebot.org/downloads/>.

That should give you an excellent starting point for designing and implementing
your own. Of course, there's also a bunch of documentation available, both in
the various download packages, and on the alicebot site.

Cheers,
Andrew

This is a messed up implementation in java(Spiritbot).  It uses
jibbler's IRC framework.

http://www.jibble.org/

My design didn't have much direction.  I may document it in the future
and actually describe my direction.

http://spiritbot.sourceforge.net/

Also, you can see javabot on the #java freenode channel.  Pretty cool,
doenst really use AI.

http://lavender.cime.net/~ricky/javabot.html