Java, A Beginner's Guide, 5th Edition, 5th Edition

Constructors, Methods, Instance Variables, and Enumerations

It is important to understand that each enumeration constant is an object of its enumeration type. Thus, an enumeration can define constructors, add methods, and have instance variables. When you define a constructor for an enum, the constructor is called when each enumeration constant is created. Each enumeration constant can call any method defined by the enumeration. Each enumeration constant has its own copy of any instance variables defined by the enumeration. The following version of Transport illustrates the use of a constructor, an instance variable, and a method. It gives each type of transportation a typical speed.

The output is shown here:

This version of Transport adds ...