Chapter 11. Collections and Maps

Exam Objectives

• Make appropriate selection of collection classes/interfaces to suit specified behavior requirements.

• Distinguish between correct and incorrect implementations of hashCode() (and equals() ) methods .

Supplementary Objectives

• Identify the core collection interfaces and their inheritance relationships: Collection , Set , SortedSet , List , Map , SortedMap .

• Understand the differences between collections and maps.

• Understand the operations performed by the addAll() , removeAll() , and retainAll() methods in the Collection interface.

• Recognize destructive and non-destructive collection operations.

• Understand how data can be passed between collections.

• Identify the implementations of the core collection interfaces and state their usage: HashSet , TreeSet , LinkedHashSet , ArrayList , Vector , LinkedList , HashMap , Hashtable , TreeMap , LinkedHashMap .

• Write code to create views on collections.

• Use an iterator to traverse all the elements of a collection.

• Distinguish between unordered, ordered, and sorted collections.

• Understand the natural ordering of elements provided by the Comparable interface and the total ordering imposed by the Comparator interface.

• State the conditions under which an UnsupportedOperationException may occur in collections.

• Identify the methods in the Collections class that can be used to produce immutable and thread-safe versions of various types of collections.

• State the major algorithms provided by the Collections class.

• Write code to pass data between arrays and collections.