CHAPTER 51 — Abstract Classes and Polymorphism

Classes in a hierarchy are related by the "is-a" relationship. For example, a Nissan is-a Automobile, and a Sentra is-a Nissan. This chapter discusses how reference variables are used for objects from different classes within a hierarchy. Another subject is the idea of an abstract class — a class that cannot be instantiated but that can be the parent of other classes.

Chapter Topics:

• Abstract Classes.
• Abstract Methods.
• Polymorphism.