The API is enough -- just make sure you pay close attention to the methods mentioned in the objectives... but there is also one error in the objectives, so here is what you DO need to know about wrappers: doubleValue, floatValue, intValue, etc. parseXxx (the parse methods) toString() toHexString() And here's the error: the formal objectives say the exam covers the getXxx methods. That is NOT correct. The exam does NOT cover the getXxx methods, however it DOES cover the valueOf() methods, so even though they are not listed in the objectives, you do need to know them!! Know especially which methods (including constructors) might throw a NumberFormatException (hint: anything that has to parse a String...) Be sure you understand also how .equals() works for Wrappers. Like, what happens if you compare two wrappers of the same type with the same value? What about two wrappers of DIFFERENT types (long and int, for example) that have the same value? And would a wrapper be acceptable as a key in a HashMap? All you need is in the API. Cheers, Kathy Of course if you happen to have an extra $34.95 US and no place to spend it... -Don't forget: a Java certification book makes a wonderful Valentine's day gift for that special someone.