I need to find an active Java mailing list, I have looked onto the GNU Java mailing list, to my surprise there had been not too much activity this month, it also focused on any GNU related Java - I'd really help me progress my Java ability, if I had an active, likeminded Java mailing list. Questions' that are not suited to Stackoverflow, or provide little benefit to any user that see's the question:
discussing a new API change;
open source discussion;
trivia type questions on Java ArrayList boxining-unboxing;
I also read Jon Skeets blog post about his previous Java/C# mailing lists examples - I did not catch any names, though I did they would be of benefit to me, if I had access to any of them.