During my course of preparation for the SCJP2 exam, I actively participated in JavaRanch's Java Programmer Certification Forum. I really enjoyed this period. I am still a co-moderator for this Java Programmer Certification forum in www.javaranch.com and I think by trying to clear others doubts we also learn a lot and it is a very good way of gauge our Java knowledge as well as many other capablities like written communication skills, coping up with others etc. I am providing some of those discussions I  participated in Javaranch.com for you objectivewise here. I planned to update these discussion pages regularly (once in a week) with new discussion threads. So check these Discussion pages regularly. I hope you will find them useful.