Key L&F Classes and Interfaces

In this section, we’ll take an in-depth look at several of the key classes and interfaces that make up the Swing pluggable look-and-feel design. Figure 26.3 shows the relationships between the classes (and interfaces) we’re going to examine in this section.

High-level look-and-feel class diagram

Figure 26-3. High-level look-and-feel class diagram

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


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 look-and-feel.


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

UIDefaults. ActiveValue and UIDefaults.LazyValue

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


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.


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

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