c++ is much better for making games than java
People argue that java is a little slower than C++, which may be true in numbers, but honestly it doesn't hinder its ability to make great games.
C++ is more difficult and complex than java and since you have already been learning java, you will prevent many headaches by sticking with java.
I won't tell you to not learn C++, it will certainly prove to be an excellent tool, but don't leave java behind just because someone said c++ was better.
Edit: I take back what I said about slapping in the face, but honestly people that think this are stuck in the days when java wasn't what it is today.