National Academy of Engineering

• Here are the 14 grand challenges.
• Which ones are CS related?

Chapter 10: Inheritance

Introduction

• Superclass - the superset or more general class
• Subclass - the subset or more specific class
• How does inheritance differ from implementing an interface? A subclass inherits behavior and state from the superclass. An interface has no behavior and no state.

Methods

• Can be inherited (if they are not private)
• Can be overridden
• Can be added

Instance Variables

• All instance variables are inherited (but can't be accessed directly if they are private)
• New instance variables can be added

Java

• Object - the superclass of every class
• extends - to create a subclass, e.g. public class Student extends Person { ... }
• super - to access the superclass
• Person p = new Student();
• Student s = (Student) p;
• instanceof = tests whether an object belongs to a particular type

Lecture Code

In lecture today, we will build an application that defines classes for the following scenario. A person has a name and a birth year. A baseball player is a person who has a team and a salary. A pitcher is a baseball player who has an ERA. A batter is a baseball player who has a batting average.

• TestProgram.java
• Person.java
• BaseballPlayer.java
• Batter.java