Nimbus provide more lively look and feel in Swing UI. Here are some examples:
Default Look And Feel(Click to see enlarged mode)


Since the image is little small and related to my Online Java Project(which I can't change), so I provide another example here from my last blog code.
Default Look And Feel


Quickest way to try, command line:
Run my previous (or any UI code) with the following option:
java -Dswing.defaultlaf=com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel LayoutCheck
Off course, you can do it with code :
UIManager.setLookAndFeel(
"com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
Use try, catch and respect Exception handling as well.