I think that learning the language is not difficult. In fact, I used to be a full time C++ developer, and at some point I started writing Java code. But the thing is that I don't remember ever learning Java, so I guess I just figured it as I went. I've been doing full time Java for a long time now.

If you are well familiar with C++, you may want to read a list of the major differences (e.g., everything is dynamically-bound) and then start practicing on an environment (just download Eclipse). The small differences are the main thing you would have to get adjusted to.

Now that Java supports generics, one of the major switching pains is gone. Multiple inheritance, while not supported, is not a big deal if you get used to interfaces, and in fact having interfaces rather than abstract classes with pure virtual functions (PVFs) improves readability.

To me Java is a nice and friendly and relaxing sandboxed version of C++. I don't have to worry about general protection faults (GPFs), I don't have to worry about memory leaks, I don't have to worry about messing with pointers. However, don't let that confuse you, there are still plenty of opportunities to screw up royally, and they're sometimes even nastier to detect.

Just take the leap. If you have the instinct, it shouldn't be a problem.