Here is an example for a TristateCheckBox:
Peter Lang
2010-04-23 20:39:58
Oh yes, but you have to create a custom component.
Take a look at this article in the Java Specialist and see if it works for you.
It needs a bit of work in OSX though.
WinXP:
If you're trying to do a tree of checkboxes (which is a common reason to need a tri state checkbox), check out Jide Commons.
Later I found a ready-made solution at http://www.ansir.ca/tristate.jsp