The term “collections” refers to the notion of objects that contain or manage other objects. Most developers are familiar with the basic collections, including the classic array (such as
String) or the built-in Java classes (such as
java.util.Hashtable). The introduction of a rich Java Collections Framework in Java 2 (JDK 1.2) brought a standardized implementation of classes for expressing more complex relationships. The Apache Jakarta Commons Collections project adds even more capability, as described in this chapter.
Table 11-1 compares some of the key differences between basic collection types. When possible, you should try to rely on the interfaces shown, not on the underlying implementation. For example, even if you ...