Exploring the Collections Framework
Applications often must manage collections of objects. Although you can use arrays for this purpose, they are not always a good choice. For example, arrays have fixed sizes, making it tricky to determine an optimal size when you need to store a variable number of objects. Also, arrays can be indexed by integers only, making them unsuitable for mapping arbitrary objects to other objects.
The standard class library provides the Collections Framework and legacy utility APIs to manage collections on behalf of applications. In Chapter 9 I first present this framework and then introduce you to these legacy APIs (in case you encounter them in legacy code). As you will discover, some of the legacy APIs ...