Java generics are cool.

This:

Collections.sort(administratableUsers,
   new Comparator<user>()
   {
       public int compare(User u1, User u2)
       {
           return u1.getUsername().compareTo(u2.getUsername());
       }
   });

is much cleaner than:

Collections.sort(administratableUsers,
   new Comparator()
   {
       public int compare(Object o1, Object o2)
       {
           User u1 = (User)o1;
           User u2 = (User)o2;

           return u1.getUsername().compareTo(u2.getUsername());
       }
   });