9.2 Superclasses and Subclasses
Often, an object of one class is an object of another class as well. Figure 9.1 lists several simple examples of superclasses and subclasses—super-classes tend to be “more general” and subclasses “more specific.” For example, a CarLoan is a Loan as are HomeImprovementLoans and MortgageLoans. Thus, in Java, class CarLoan can be said to inherit from class Loan. In this context, class Loan is a superclass and class CarLoan is a subclass. A CarLoan is a specific type of Loan, but it’s incorrect to claim that every Loan is a CarLoan—the Loan could be any type of loan.
Fig. 9.1 Inheritance examples.
| Superclass | Subclasses |
|---|---|
| Student | GraduateStudent, UndergraduateStudent |
| Shape | Circle, Triangle, Rectangle, ... |
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