Is there any excuse not to know Java?
cj_basu: I can't think of any valid excuse. Quite a few very good open source projects are in java and it will be highly beneficial if you know Java to use the code for your own purposes. Also I believe Java is one of the heavily used language in the industry currently if not THE most used. And it is also a well designed object oriented language (so I find no harm in learning it). It is also a good entry into the Java platform/ecosystem.