Learned Java on my own a couple years ago, but have never used it in a professional environment. Do a lot of Python on my own. Do C/perl/bash/some C++ at work.
Love Python, Java is OK.
Then again, I've never used github neither personally nor professionally, I'm gonna guess these results are biased heavily towards github users, the rest of us (Perforce for me) are completely left out.
/ several years ago we were writing a new test suite
// I wanted Python, most others wanted Perl
/// Boss said "3,000 engineers here know Perl, you know Python. Wanna support 3,000 engineers?"
//// bummer, but he had a damned valid point