Awesome

miglayout

Official MiG Layout for Swing, SWT and JavaFX

For Java developers writing GUI layouts by hand that wants simplicity, power and automatic per platform fidelity, that are dissatisfied with the current layout managers in Swing, JavaFX and SWT, MigLayout solves your layout problems. User interfaces created with MigLayout is easy to maintain, you will understand how the layout will look like just by looking at the source code.

MigLayout is a superbly versatile JavaFX/SWT/Swing layout manager that makes layout problems trivial. It is using String or API type-checked constraints to format the layout. MigLayout can produce flowing, grid based, absolute (with links), grouped and docking layouts. You will never have to switch to another layout manager ever again! MigLayout is created to be to manually coded layouts what Matisse/GroupLayout is to IDE supported visual layouts.

For documentation see http://miglayout.com