RelativeLayout, a Constraint-Based Layout Manager (O'Reilly)
Layout managers fall firmly into the periphery when talking about Swing. They're something you use all the time with Swing containers, but they predate Swing and you can use them just as well with an AWT application. Still, layout managers play such a fundamental role in arranging the pieces of your user interface that you need to develop a good understanding of at least a couple of them so that you can work effectively. And they hold the promise of enabling your application to look polished as it moves from platform to platform, gracefully adapting to new font metrics and component shapes."