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 can be the parent of other classes.

Chapter Topics:

• Abstract Classes.
• Abstract Methods.
• Polymorphism.

QUESTION 1:

How many Valentine cards did you get this year?