I haven't sat the exam yet (planning on sitting it in three weeks), but I've covered most of the topics, and there's no particular reason you need to use Java when learning this stuff. It would help if you could read Java (which
you should be able to with the C++ experience you have), as a lot of examples are done in Java (as you noted), but I haven't written any Java code in my study, though I have been doing lots of examples and investigations.
In fact, when doing examples, you may find it easier to use a scripting language instead.