[Fubarable]

You either need to import java.util.Comparator or use fully qualified names, i.e.,

      java.util.Vector<Contact> book = new java.util.Vector<Contact>();

      java.util.Collections.sort(book, new java.util.Comparator<Contact>() {

         public int compare(Contact p1, Contact p2) {
            return p1.getsecondName().compareToIgnoreCase(p2.getsecondName());
         }
      });