Hi Sanjana,
I think one should have a good view of the following classes.
Vector
Collection
Set
List
I think the best way have a good knowledge of java.util is to take the mock
test and then find out what classes occures regulary there.Make a seperate
notes for major points related to
SCJP.
Like
Set can't have dupilicate.
At the top of the util hierarchy is a Collection class and not Collection interface.
Don't waste too much time on knowing the details of each and every class
and Interface.
If anything u would like to correct then plz do it.