Besides enhanced looks and ADVANCED features, one of the best things about Swing is its pluggable look and feel (PLAF). PLAF architecture allows seamless changes in the appearance of an application and the way an application interacts with the user. However, designing and developing a PLAF is much more exhaustive and complex. On the other hand, themes provide a simple alternative to change look and feel of the swing application. Themes are easier to implement and they enhance the visual appeal of the application UI using the default Java look and feel.
Theme mechanism allows a developer to easily specify the default colors, fonts and icons used by the look and feel (L&F). It allows developers to write their own themes giving them a choice to show their application GUI the way they want it, rather than depending on the defaults provided by the system.
