// Comparator to sort in natural ascending order
public class Natural implements Comparator
   {

   /**
   * Compare two objects by their natural orders
   *
   * @param a first object to be compared
   *
   * @param b second object to be compared
   *
   * @return +1 if a>b, 0 if a=b, -1 if a<b
   */
   public final int compare ( Object a, Object b )
      {
      return( (Comparable)a ).compareTo ( b );
      }
   }