Post Lab 9: Rolling a Pair of Dice

Due Monday, November 14, 2011 by 4 p.m.

The PairOfDice class must meet the following specifications:

Instance data: Two Die objects (die1 and die2). You need to save the class Die.java from your textbook (it is on pages 168 - 169 - an example program that uses Die objects is on page 167). Do not change Die.java - just use it. For example, you will declare the two instance variables die1 and die2 to be of type Die in your PairOfDice class.

Methods:

• a constructor with no parameters - the constructor should instantiate each Die object.
• a method roll that rolls each die (use the method in the Die class - rolling a pair of dice involves rolling each single die!) and returns the sum of the face values. The method should have no parameter.
• a method isDoubles that returns true if the face values on the two dice are the same ("doubles") and false otherwise. Note that you do not need to use an if - you can do this with a single return statement. (Again, you need to use methods in the Die class here and in the following methods.)
• a toString method that returns the PairOfDice object as a string in the following format (assuming the first die is a 2 and the second a 5):

         [ 2 : 5 ]
  

• a method getTotalRoll that returns the total of the face values on the two dice (this method DOES NOT roll the dice again - it just returns the total of the current face values).

Write a program PlayGame that does the following:

• Instantiates a PairOfDice object.
• Rolls the pair of dice and saves the value of the roll (call this point).
• Prints out the first roll, appropriately labeled. (Print the "roll" - that is, print the object which shows the values on each die - not just the total.)
• Next keep rolling the dice until you roll point again (the variable point does not change - the goal is to roll the same total as your first roll). Count the number of times you roll and the number of times that you get doubles. Print out each roll. Note that this needs a loop. We'll use a do loop. The general structure will be as follows:

         // Roll for point (as described above)
  
  
         // Loop set up - initialize the counting variables (one for number 
         // of rolls and one for doubles) and roll the dice to get a new roll
   
         do
         {
             //  roll the dice
  
             //  print the current dice, appropriately labeled
  
             //  increment the count for the number of rolls
  
             //  if the roll is doubles increment the doubles counter
  
         }
         while the new roll is not equal to point
  

• After the loop print out the number of rolls it took to match point (appropriately labeled) and the number of doubles that were rolled while you were rolling the dice.

Other requirements: As usual you must use good programming techniques. Each of your files must be documented appropriately!

Submission:

• Submit a zip file of your post lab directory to Inquire.