Yes and you must know the differences between them and when to use one as opposed to another. ------------------ Tom - SCJP --- Co-Moderator of the Programmer Certification Forums
The interfaces are: Collection Set SortedSet List Map SortedMap
The inheritance hierachy is arranged something like this (hopefully the formatting works): Collection ----> Set ------> SortedSet | ----> List Map -------> SortedMap
With a little knowledge, a cast iron skillet is non-stick and lasts a lifetime.