This week's giveaway is in the EJB and other Java EE Technologies forum. We're giving away four copies of EJB 3 in Action and have Debu Panda, Reza Rahman, Ryan Cuprak, and Michael Remijan on-line! See this thread for details.
Mughal has a nice set of diagrams showing the main collection interfaces and classes. What to study: Collections class Collection interface List interface Iterator interface ListIterator interface Vector class ArrayList class LinkedList class Set interface TreeSet class Map interface HashMap class Hashtable class Comparator interface Comparative interface -anthony