/* An instance of this class represents a coin that can be tossed,
** (pseudo-randomly) resulting in either HEADS or TAILS (with equal
** probabilities). 
*/
public class TossableCoin {

   // instance variable
   // -----------------

   private boolean headsShowing;  // true if HEADS, false if TAILS

   /* Initializes this tossable coin to be "showing" HEADS.
   */
   public TossableCoin() {
      headsShowing = true;
   }

   // observers
   // ---------

   /* Reports whether this coin is showing HEADS.
   */
   public boolean isHeads() { return headsShowing; }

   /* Reports whether this coin is showing TAILS.
   */
   public boolean isTails() { return !headsShowing; }

   /* Returns a string indicating which of the two faces
   ** is showing.
   */
   public String toString() {
      String result;
      if (isHeads()) 
         { result = "HEADS"; }
      else 
         { result = "TAILS"; }
      return result;
   }


   // mutators
   // --------

   /* Simulates a tossing of this coin, which is intended to be "fair",
   ** meaning that each of HEADS and TAILS should result half the time.
   */
   public void toss() {
      headsShowing = Math.random() < 0.5;

      //Note that the code above is equivalent to the more verbose
      //
      // if (Math.random()) < 0.5) 
      //    { headsShowing = true; }
      // else 
      //    { headsShowing = false; }
   }

}