JeaIRC is a free and easy to use (+ open source!) IRC library for Java.
Some time ago I searched for Java IRC libraries and I even found some,
but they were either too hard to use or didn't work at all, so I decided to
write one myself.
JeaIRC means Java Endless Aerospace IRC and is the library itself. To be
able to test the library as I wrote it, I also wrote an IRC bot called
JeaB, which means Java Endless Aerospace Bot and is also free to use.
It is based on plugins (written in Java), so it's easy to add functionality
without having to read through the whole source code.
Both JeaIRC and JeaB are written in Java7, that means that they should work
on every system which has Java7 installed.
Java6 or lower are not supported!
You can download the J(ava) R(untime) E(nvironment) or the J(ava) D(evelopment)
K(it) here
If you only want to use the bot or the library on your server / home, you only
need the JRE. If you want to develop and write your own code (e.g. plugins)
you need to download the JDK.

Feel free to join my IRC channel:
irc.quakenet.org #endless-aerospace
You can also use the webchat:
Webchat