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

5.3. Defining Methods

You have been producing versions of the main() method since Chapter 1, so you already have an idea of how a method is constructed. Nonetheless, I'll go through how you define methods from the beginning to make sure everything is clear.

I'll start with the fundamental concepts. A method is a self-contained block of code that has a name, and has the property that it is reusable—the same method can be executed from as many different points in a program as you require. Methods also serve to break up large and complex calculations that might involve many lines of code into more manageable chunks. You execute a method by calling it using its name, and the method may or may not return a value when its execution finishes. Methods that do not return a value are always called in a statement that just specifies the call. Methods that do return a value are usually called from within an expression, and the value that is returned by such a method is used in the evaluation of the expression. If a method that returns a value is called by itself in a statement, not in an expression in other words, then the value it returns is discarded.

The basic structure of a method is shown in Figure 5-2.

Figure 5.2. Figure 5-2

When you specify the return type for a method, you are defining the type for the value that will be returned by the method when you execute it. The method must ...