depends on you. how easily do you learn new programming languages? My opinion: c++ is more difficult to learn mainly because it will let you stab yourself in the back. If I were you, I would learn both languages -- but not at the same time.
I would say that C++ is definitely harder to learn and understand than Java. When you are using C++ it is really easy to forget/misuse a lot of the object oriented methodology. With Java, programming is a lot simpler. The code that you write will more than likely turn out clear and easy to read. In any case, the concepts are really what matter when you are learning how to program, and if you can do it in a clean and tidy language (and manner!) then it will only improve your understanding.
If you already know C++ then Java is going to be the easiest thing in the world to learn. The syntax is practically the same with only a few exceptions (and a lot of limitations). Java is so C++ like that I have seen it take as little as a day for an experienced C++ programmer to get comfortable in Java. Of course, Java was modelled after C++, so that is to be expected. :lol:
Oh, and I have to take a Java class next semester too. Hehe.