Ok listen up,
first you'll be asked to take a survey
and act as if you "know hardly anything about java" I tried to be a good programmer and
regret it.
Time was ample, I had 50 minutes to spare after rechecking.
Cover generic collections THOROUGHLY (You're in trouble if you're not sure which declarations will work for what methods)
Cover Garbage colletion very FINELY
Cover threads very DEEPLY
java.util.text, as Bert said, important constructors and methods.
And don't you go ignoring access modifiers just because some T,D or H told you. There were questions that had me blinking for a couple of minutes before the right solution struck me.
Get Serialization/Deserialization very clearly
Make hierarchy charts for Exceptions, Collections, I/O classes <<they help like hell.
Cover Exception Handling with a lot of emphasis on flow control
Don't get rattled by heavy words like coupling, cohesion etc, if you know english and have good common sense, you can do it.
Cover I/O well, do a lot of strean wrapping examples and remember which methods belong where.
Do your JLS examples too, many were minor modifications.
TIP: Even if your sure about your answer, just look at the options and just try to see how they might fit, it happens that u might accidentally hit upon the right one and realize it only later.