I just updated to the public beta of OS X Yosemite. When working with Swing, I notice that the components are not optimized. What I mean is that the buttons look like they are from Mavericks (10.9) instead of Yosemite (10.10). If you don't understand what I mean, I can provide screenshots. Is there any property I can change or is it something that Oracle needs to do?
Oracle now manages the UI delegates used by the Apple Look & Feel as part of OpenJDK,
com.apple.laf.AquaLookAndFeel
You can see the sources here, but you may want to wait for Oracle to incorporate them into a future build.