If you poke around the Java home page ( g), you’ll find Swing described as a set of customizable graphical components whose look-and-feel (L&F) can be dictated at runtime. In reality, however, Swing is much more than this. Swing is the next-generation GUI toolkit that Sun Microsystems created to enable enterprise development in Java. By enterprise development , we mean that programmers can use Swing to create large-scale Java applications with a wide array of powerful components. In addition, you can easily extend or modify these components to control their appearance and behavior.
Swing is not an acronym. The name represents the collaborative choice of its designers when the project was kicked off in late 1996. Swing is actually part of a larger family of Java products known as the Java Foundation Classes ( JFC), which incorporate many of the features of Netscape’s Internet Foundation Classes (IFC) as well as design aspects from IBM’s Taligent division and Lighthouse Design. Swing has been in active development since the beta period of the Java Development Kit ( JDK) 1.1, circa spring of 1997. The Swing APIs entered beta in the latter half of 1997 and were initially released in March 1998. When released, the Swing 1.0 libraries contained nearly 250 classes and 80 interfaces. Growth has continued since then: at press time, Swing 1.4 contains 85 public interfaces and 451 public classes.
Although Swing was developed separately from the core Java Development Kit, it does require at least JDK 1.1.5 to run. Swing builds on the event model introduced in the 1.1 series of JDKs; you cannot use the Swing libraries with the older JDK 1.0.2. In addition, you must have a Java 1.1-enabled browser to support Swing applets. The Java 2 SDK 1.4 release includes many updated Swing classes and a few new features. Swing is fully integrated into both the developer’s kit and the runtime environment of all Java 2 releases (SDK 1.2 and higher), including the Java Plug-In.
The FC is a suite of libraries designed to assist programmers in creating enterprise applications with Java. The Swing API is only one of five libraries that make up the JFC. The JFC also consists of the Abstract Window Toolkit (AWT), the Accessibility API, the 2D API, and enhanced support for Drag and Drop capabilities. While the Swing API is the primary focus of this book, here is a brief introduction to the other elements in the JFC:
AWT
The Abstract Window Toolkit is the basic GUI toolkit shipped with all versions of the Java Development Kit. While Swing does not reuse any of the older AWT components, it does build on the lightweight component facilities introduced in AWT 1.1.
Accessibility
The accessibility package provides assistance to users who have trouble with traditional user interfaces. Accessibility tools can be used in conjunction with devices such as audible text readers or braille keyboards to allow direct access to the Swing components. Accessibility is split into two parts: the Accessibility API, which is shipped with the Swing distribution, and the Accessibility Utilities API, which is distributed separately. All Swing components support accessibility, so this book dedicates an entire chapter (Chapter 25) to accessibility design and use.
2D API
The 2D API contains classes for implementing various painting styles, complex shapes, fonts, and colors. This Java package is loosely based on APIs that were licensed from IBM’s Taligent division. The 2D API classes are not part of Swing, so they are not covered in this book.
Drag and Drop
Drag and Drop (DnD) is one of the more common metaphors used in graphical interfaces today. The user is allowed to click and “hold” a GUI object, moving it to another window or frame in the desktop with predictable results. The DnD API allows users to implement droppable elements that transfer information between Java applications and native applications. Although DnD is not part of Swing, it is crucial to a commercial-quality application. We tackle this topic in Chapter 24.