It's not adaptive and it is only difficult in the sense that you have to know the subject well. Part of the trick is to ensure you spend your time well by getting a good understanding of the things that can come up, and don't worry too much about the rest of the stuff you can learn over the rest of your Java career.
Thus for example, although it requires a good knowledge of some aspects of Threading, areas of Threading are not tested at all (ie you can be ignorant of ThreadGroup). But if you don't know the signature of the the run method and the requirements for the use of wait/notify you might be tripped up.
Marcus
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