import java.util.*;

/**
     A Comparator class that keeps track of the number of times
     that its <code>compare</code> method is invoked.
     The corresponding comparison counter can be queried and
     reset to 0.
  */
  // The default constructor is adequate for this class.


  public class CountingComparator implements Comparator
  {

    int counter = 0;        // the comparison counter


    /**
      Compares two objects according to the Comparator contract.
      @param o1 the first object
      @param o2 the second object
      @return an integer
       which is negative if the first object is smaller
                positive if the first object is larger
                and zero if neither object is larger
       according to the <code>compareTo</code> method
       for the first object
      @throws a ClassCastException if the first object
       is not comparable, or would throw such an exception
       when sent the <code>compareTo</code> message and the
       second object
     */

    public int compare(Object o1, Object o2)                {
      if (o1 instanceof Comparable)                 {
        counter++;
        return ((Comparable) o1).compareTo(o2);     }
      else
        throw new ClassCastException();                     }


    /**
      @return the current value of the comparison counter
    */

    public int getCounter()                                 {
      return counter;                                       }


    /**
      Resets the comparison counter to 0.
    */

    public void resetCounter()                              {
      counter = 0;                                          }

  }