The Collections API provides a useful set of interfaces and classes that can be used for building data structures that represent collections of data. The emphasis in this course is on how to make effective use of this API rather than on how to implement the various data structures.

The course describes and explains the differences between the capabilities of the three main interfaces called List, Set and Map (and subinterfaces called SortedSet and SortedMap), and the six classes called ArrayList, LinkedList, HashSet, TreeSet, HashMap and TreeMap. The use of the Iterator interface is also described.

Once again, the stress is to write the code of clients in terms of the interface, only mentioning the name of a class when you want to create a collection object.

Although later lectures show how to implement the List interface by (a) an array and (b) a doubly linked list, this only appears after extensive use in earlier lectures of the List, Set and Map interfaces.