Presently, i am learning Java from the book The Art and Science of Java and following Standford’s Programming Methodology Course.
I would like to do game programming, but only as a hobby.
I was thinking, would Java be a good choice or is C++ the defacto in game programming.
Since you are learning Java i would recommend that you stick to it.
If you are only developing games for fun, it won’t really matter what language you use.