Android How to Program

G. Object-Oriented Programming: Inheritance and Polymorphism

Objectives

In this appendix you’ll:

• Learn how inheritance promotes software resuse.

• Understand the relationships between superclasses and subclasses.

• Use keyword extends to effect inheritance.

• Use protected to give subclass methods access to superclass members.

• Reference superclass members with super.

• Learn the methods of class Object.

• Learn the concept of polymorphism.

• Use overridden methods to effect polymorphism.

• Distinguish between abstract and concrete classes.

• Declare abstract methods to create abstract classes.

• Learn how polymorphism makes systems extensible and maintainable.

• Determine an object’s type at execution time.

• Declare and implement interfaces. ...