The exam requires you to know which collections class is most appropriate for a particular application. If you take a quick look at the javadoc for the WeakHashMap then you will have all of the information that you might need for the exam. My mock exam has a question or two on the WeakHashMap, but I don't know how much emphasis the real exam might place on that class. I know that the real exam that I had didn't have any questions on the WeakHashMap, but I can not guarantee that your exam won't have any. The two new classes that were added to the 1.4 version of Java and the exam, LinkedHashMap and LinkedHashSet have a higher probability of showing up on your exam. The JavaRanch Newsletter has had some tutorials on the collections framework. Just search on Collections on the newsletter page.
Dan Chisholm<br />SCJP 1.4<br /> <br /><a href="http://www.danchisholm.net/" target="_blank" rel="nofollow">Try my mock exam.</a>