IN THIS CHAPTER
Programming with class (and with style and finesse)
Making objects from classes
Joining the exclusive “I understand classes and objects” society
Chapters 6, 7, and 8 introduce Java’s primitive types — things like
boolean. That’s great, but how often does a real-world problem deal exclusively with such simple values? Consider an exchange between a merchant and a customer. The customer makes a purchase, which can involve item names, model numbers, credit card info, sales tax rates, and lots of other stuff. A purchase is more complicated than an
int value. It’s more complicated than a
double value. How do you represent an entire purchase in a Java program?
In older computer programming languages, you treat an entire purchase like a big pile of unbundled laundry. Imagine a mound of socks, shirts, and other pieces of clothing. You have no basket, so you grab as much as you can handle. As you walk to the washer, you drop a few things — a sock here and a washcloth there. This is like the older way of storing the values in a purchase. In older languages, there’s no purchase. There are only
double values, ...