Ivor Horton's Beginning Java™ 2, JDK™ 5th Edition

1.5. Object-Oriented Programming in Java

As I said at the beginning of this chapter, Java is an object-oriented language. When you use a programming language that is not object-oriented, you must express the solution to every problem essentially in terms of numbers and characters—the basic kinds of data that you can manipulate in the language. In an object-oriented language like Java, things are different. Of course, you still have numbers and characters to work with—these are referred to as the primitive data types—but you can define other kinds of entities that are relevant to your particular problem. You solve your problem in terms of the entities or objects that occur in the context of the problem. This not only affects how a program is structured, but also the terms in which the solution to your problem is expressed. If your problem concerns baseball players, your Java program is likely to have BaseballPlayer objects in it; if you are producing a program dealing with fruit production in California, it may well have objects that are Oranges in it. Apart from seeming to be an inherently sensible approach to constructing programs, object-oriented programs are usually easier to understand.

In Java almost everything is an object. If you haven't delved into object-oriented programming before, or maybe because you have, you may feel this is a bit daunting. But fear not. Objects in Java are particularly easy. So easy, in fact, that you are going to start out by understanding some ...