Developing Java Beans

JavaBeans Overview

The JavaBeans white paper defines a Bean as follows:

A Java Bean is a reusable software component that can be manipulated visually in a builder tool.

Well, if you have to sum it up in one sentence, this is as good as any. But it’s pretty difficult to sum up an entire component architecture in one sentence. Beans will range greatly in their features and capabilities. Some will be very simple and others complex; some will have a visual aspect and others won’t. Therefore, it isn’t easy to put all Beans into a single category. Let’s take a look at some of the most important features and issues surrounding Beans. This should set the stage for the rest of the book, where we will examine the JavaBeans technology in depth.

Properties, Methods, and Events

Properties are attributes of a Bean that are referenced by name. These properties are usually read and written by calling methods on the Bean specifically created for that purpose. A property of the thermostat component mentioned earlier in the chapter could be the comfort temperature. A programmer would set or get the value of this property through method calls, while an application developer using a visual development tool would manipulate the value of this property using a visual property editor.

The methods of a Bean are just the Java methods exposed by the class that implements the Bean. These methods represent the interface used to access and manipulate the component. Usually, the set of public methods defined by the ...