Chapter 15
Fancy Reference Types
IN THIS CHAPTER
Writing and using a Java interface
Working with abstract classes
In previous chapters, you may have read about the things that full-time and part-time employees have in common. In particular, both the FullTimeEmployee and PartTimeEmployee classes can extend the Employee class. That's nice to know if you're running a small business, but what if you're not running a business? What if you're taking care of house pets?
This chapter explores the care of house pets and other burning issues.
Java's Types
Chapter 4 explains that Java has these two kinds of types:
- Primitive types: Java has a total of eight primitive types: The four you use most often are
int,double,boolean, andchar. Reference types: Java's API has thousands of reference types, and, when you write a Java program, you define new reference types.
Java's
Stringtype is a reference type. So are Java'sScanner,JFrame,ArrayList, andFiletypes. MyDummiesFrameis a reference type. In Chapter 8, you create your ownEmployee,FullTimeEmployee, andPartTimeEmployeereference types. Your first You'll love Java! program has amainmethod inside of a class, and that class is a reference type. You may not realize it, but every array belongs to a reference type.
In Java, reference ...