Is there a swing library that can take its layout from an XMl file?
CookSwing
And here is a large list
SWIXML http://www.swixml.org/ is all what u need.
Jakarta Jelly And I believe that you can use Spring framework to build UI applications. If you are using Spring you can configure application using the Spring XML.
JFCML: http://jfcml.sourceforge.net/