/* An instance of this class represents a six-sided die that can be rolled,
** yielding as an outcome an integer in the range 1..6.
** A die "remembers", for each outcome, how many times it was rolled.
** It does this by maintaining a six-element array, which is a vast
** improvement over using six separate variables (as was done in the
** previous version of this class).
**
** Author: R. McCloskey
*/

public class SixSidedDie2 {

   // fields (instance variables)
   // ---------------------------

   private int dotsShowing; // # of dots currently showing (in range 1..6)
   private int[] rollCntr;  // For each possible outcome (1..6), stores the # of 
                            // rolls of this die that have resulted in that outcome.
                            // Specifically, rollCntr[i] stores the # of times that
                            // i+1 has been the result of a roll.

   // constructor
   // -----------

   /* Initializes this die to be showing one dot and to not have been rolled.
   */
   public SixSidedDie2() { 
      dotsShowing = 1;
      rollCntr = new int[6];  // creates an array of int's of length six
   }


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

   /* Returns # dots currently showing (which, except before the first time it
   ** was rolled, means the result of the most recent roll of this die).
   */
   public int dotsShowing() { return dotsShowing; }


   /* Returns # times k was the outcome of a roll of this die.
   ** precondition: 1 <= k <= 6
   */
   public int rollCounter(int k) { return rollCntr[k-1]; }


   /* Returns # times this die has been rolled.
   */
   public int rollCounter() { 
      // Compute the sum of the elements in rollCntr[] and return it.
      int sum = 0;
      for (int i=0; i != 6; i++) 
         { sum = sum + rollCntr[i]; }
      return sum;
   }


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

   /* Rolls this die.
   */
   public void roll() {
      // To compute the outcome of a roll, generate a pseudorandom real 
      // number in the interval [0,1), multiply it by 6 to obtain a
      // pseudorandom real number in the interval [0,6), then take its 
      // floor (by casting to an int) and add 1.
      dotsShowing = (int)(6 * Math.random()) + 1;

      // Increment the appropriate element of the rollCntr[] array.
      rollCntr[dotsShowing-1]++;
   }

}