Newsletter sign-up

View all newsletters

Sign up for our technology specific newsletters.

Enterprise Java

Email Address:

Building a bevy of beans: Create reusable JavaBeans components

With the basics of beans in the bag, you're now ready to see how easy it is to develop more advanced beans

By Merlin Hughes, JavaWorld.com, 09/01/97

In this short series, we are examining the development of JavaBeans software components. Ultimately, most beans will be manipulated in a beans development environment; however, we are only concerned here with the source-level aspects of the framework. The advantages of developing JavaBeans -- that is, developing to the JavaBeans specification -- are severalfold, among them:

• Beans can be easily manipulated in visual development environments by users who need not be technically skilled in source-level Java development.
  
  
• Because of the standard interface, beans are readily distributable, which allows third-party components to be more easily integrated into development efforts.
  
  
• Developers can easily transfer code that has been developed for one project into a reusable library of components, which can be accessed in future development efforts.

The eye of the storm

In the first part of this series, we developed two simple beans: a non-visual alarm bean and a graphical left-arrow/right-arrow bean. Both were augmented with visual customizer and bean information classes. In the beans we cover this month, we won't be providing customizers; instead, we'll concentrate on using existing beans and components to create bigger, better beans.

Prerequisites
As the continuation of a two-part series, I will assume familiarity with the issues discussed in the previous installment, including the supplementary articles and resources.

The beans
From start to finish of this series, we develop the following beans:

AlarmBean

A non-graphical bean that fires off an event after a specified delay.

ArrowBean

A graphical left-arrow/right-arrow bean.

ProgressBean		A graphical progress-display bean.
NumberFieldBean		A graphical numeric TextField bean with roll buttons. This bean makes use of the ArrowBean bean.
FontChooserBean		A graphical font-chooser bean. This bean makes use of the NumberFieldBean bean.
FontSelectorBean		A graphical font-chooser bean that displays the current font and provides OK/Cancel buttons. This bean makes use of the FontChooserBean bean.
FontDialogBean		A graphical font-chooser bean that pops up the font selector in a separate dialog. This bean makes use of the FontSelectorBean bean.

We discussed the AlarmBean and ArrowBean beans in detail last month; in this episode, we will discuss the remaining beans in varying levels of detail.

You may be wondering why we're building three font beans. The ultimate goal is simply to produce a font selector bean that pops up a font dialog when the user clicks on a button. This task very naturally divides into the three beans we'll produce: The first is the user interface for the font selection, the second adds dialog controls and a font sample, and the third introduces a button to pop up the dialog and contains the basic dialog-handling code.

Without beans, we would have to develop these items as specialized AWT components or as a single monolithic class; using beans, we can develop the three parts as independent beans that are reusable in their own right.

 

Improve efficiency with Visual Studio(r) 2010 Beta 2. - Microsoft

About Us | Advertise | Contact Us | Terms of Service/Privacy

Copyright, 2006-2008 Network World, Inc. All rights reserved.