I believe that it means that if you have a private constructor, for example:
That
you should include a public/protected static method for getting an instance (object) of the class, ala the singleton approach:
It lets you do things like make sure only one instance of a class is instantiated at any one time, or only allow certain sources instantiate
an object, etc.
I hope this helps. If you need further reading, might I suggest the singleton tutorial over at sun:
http://java.sun.com/developer/technicalArticles/Programming/singletons/ Its written by someone with a fantastic last name, though obviously not as a cool a first name as mine

[ May 10, 2004: Message edited by: Jason Fox ]