1) If you have z coordinates, then you may not have a polygon.  Are you  
sure that the points all lie in the same plane?

2) In three dimensions, "clockwise" and "counter-clockwise" don't really  
mean much without a specific reference point, since you could view the  
polygon from either side.

2) If the points represent a polygon, then they must already be ordered.  
You're not looking for a way to sort them, but rather a way to figure out  
whether they are already in clockwise order, and if not then you know to  
reverse their order so that they are.

As far as the actual approach, here's one possible solution: you can use  
vector dot and cross products to determine a signed angle between segments  
of your polygon (dot product can tell you the angle, cross product can  
tell you which direction/sign).  Arbitrarily assign positive angles as one  
direction and negative angles as the other (left or right, clockwise or  
counter-clockwise).  Then add all of the angles for each apex of the  
polygon.  The sign of the final sum will tell you whether the polygon is  
clockwise or counter-clockwise.

That may or may not be the most efficient solution.

Not that any of this has anything to do with Java.  If the above doesn't  
give you enough information, I recommend doing some research on your own.  
Or ask your teacher.  :)

Pete

see http://mindprod.com/jgloss/sort.html

If the class  that describes the points does not support a natural
Comparable  ordering, extend the class and write one, or implement an
Comparator.  see http://mindprod.com/jgloss/comparable.html
http://mindprod.com/jgloss/comparator.html