Data Structures and the Java Collections Framework, Third Edition

CHAPTER 4

The Java Collections Framework

The Java Collections Framework is an assortment of related interfaces and classes in the package java.util. For most of the classes in the Java Collections Framework, each instance is a collection, that is, each instance is composed of elements. The collection classes can have type parameters, a new feature of Java, so that a user can specify the type of the elements when declaring an instance of a collection class. In this chapter, we will take a brief tour of the Java Collection Framework's collection classes, along with the new features that enhance the utilization of those classes.

CHAPTER OBJECTIVES

1. Understand what a collection is, and how contiguous collections differ from linked collections.
2. Be able to create and manipulate parameterized collections.
3. Identify several of the methods in the Collection interface.
4. Describe a design pattern in general, and the iterator design pattern in particular.
5. Compare the ArrayList and LinkedList implementations of the List interface.
6. Be able to utilize boxing/unboxing and the enhanced for statement.

4.1 Collections

A collection is an object that is composed of elements. The elements can be either values in a primitive type (such as int) or references to objects. For a familiar example, an array is a collection of elements, of the same type, that are stored contiguously in memory. Contiguous means "adjacent," so the individual elements are stored next to each other¹. For example, we can create ...