Java Swing, 2nd Edition

Key Look-and-Feel Classes and Interfaces

In this section, we’ll take an in-depth look at several key classes and interfaces that make up the Swing PLAF design. Figure 26-4 shows the relationships between the classes (and interfaces) we will examine in this section.

Figure 26-4. High-level L&F class diagram

Before we look at the details of each of these classes, we’ll quickly describe the role each one plays:

LookAndFeel

The abstract base class from which all the different L&Fs extend. It defines a number of static convenience methods, as well as some abstract methods required by every L&F.

UIDefaults

An L&F is responsible for defining a set of default properties. UIDefaults is a Hashtable subclass that holds these properties. The properties include UIClassID to ComponentUI subclass mappings (e.g., "TreeUI" to MetalTreeUI) as well as lower-level defaults, such as colors and fonts.

UIDefaults.ActiveValue and UIDefaults.LazyValue

These inner interfaces of UIDefaults enable some optimizations for resource values.

UIResource

This is an empty interface (like Serializable or Cloneable) used to tag property values. It allows values defined by the L&F to be distinguished from values set by the user, as described in Section 26.3.5 later in this chapter.

UIManager

If you’ve ever changed the L&F of a Swing program at runtime, you’re probably already familiar with this class. UIManager is responsible ...