A collection allows a group of objects to be treated as a single unit. Arbitrary objects can be stored, retrieved, and manipulated as elements of collections.
Program design often requires handling of groups of objects. The collections framework presents a set of standard utility classes for managing such collections. This framework is provided in the java.util package and comprises three main parts:
The core interfaces that allow collections to be manipulated independently of their implementation (see Figure 11.1 and Table 11.1). These interfaces define the common functionality exhibited by collections and facilitate data exchange between collections.
A small set of implementations ...