Elephant.java

import java.util.List;
import java.util.ArrayList;
import java.util.Scanner;

public final class Elephant  {

   private static int count = 0;     // to generatate unique ids
   public final int uid, weight, iq;

   private Elephant (final int i, final int w, final int s) {
      uid=i; weight=w; iq=s;
   }

   // Elephants id numbers are 0, 1, 2, ...
   public  Elephant (final int w, final int s) { this (count++, w, s); }

   public boolean heavierAndDumberThan (final Elephant e) {
      return this.weight > e.weight && this.iq < e.iq;
   }

   // NB. "public" is necessary.
   @java.lang.Override
   public String toString () {
      return String.format ("%03d [%d,%d]", uid, weight, iq);
   }

   /*  Equality Note.
       Every instance of the class 'Elephant' denotes a different
       elephant.  So two elephants are the same iff e1==e2.  And
       since 'equals' is not overriden e1==e2 if 'e1.equals(e1)'
       (under most conditions).
   */

   public static void main (final String[] args) {
      final Scanner scan = new Scanner (System.in);

      // Read in elephants from standard input; add to collection
      final List<Elephant> list = new ArrayList<Elephant> ();
      while (scan.hasNextInt()) {
         list.add (new Elephant (scan.nextInt(), scan.nextInt()));
      }
      System.out.println (list);
   }
}