Java has a huge open-source ecosystem that you could search for contributors with junior level skills. And some projects are interesting enough to warrant hobby

Java has a huge open-source ecosystem that you could search for contributors with junior level skills. And some projects are interesting enough to warrant hobbyists to play around with them just for the heck of it. For example, I'm looking to start studying computer graphics and I'm looking into playing around with JOGL instead of getting my hands around C++ (not that C++ sucks, its just that I wanted to ease myself into it). I'm getting pulled into non-Java JVM languages though, so Java doesn't look all too promising for me as a hobby language. At the very least, you could look into somebody having Clojure or Scala skills, they'll probably have knowledge of the JVM and Java would be just easy for them to pick up.