PircBot is a Java framework for writing IRC bots quickly and easily.
Its features include an event-driven architecture to handle common IRC
events, flood protection, DCC support, ident support, and more. Its
comprehensive logfile format is suitable for use with pisg to generate
channel statistics.

Full documentation for PircBot's API is included, and its homepage
contains a 5-minute step-by-step guide to making your first IRC bot.