Example: A Game of Chance

The Rules of Crap

• A player rolls 2 dice, each of which has 6 faces, numbered 1 - 6.
• If the sum of the dice is 7 or 11, the player wins.
• If the sum of the dice is 2, 3, or 12, the player loses.
• Otherwise, the sum of the dice becomes the player's point.
• To win, the player must roll that sum again before rolling a sum of 7.
• Otherwise, the player loses.

Program Comments

• Method rollDice is invoked from 2 points in the applet. (Is that necessary?)
• It returns the sum of the 2 dice, hence the return type of int.
• Taking no arguments, it always generates 2 random numbers in the interval [1, 6].
• The int variable gameStatus and the boolean variable firstRoll record the state of the game:
  • gameStatus has 3 possible values: WON, LOST, and CONTINUE.
  • The keyword final preceding their int declaration indicates that the value of these variables is not to be changed at execution.
  • Capitalization of such variables is a programmer custom that goes back to the C programming language.
• We use a GUI component that we've not used before: a Button.
• Our action method is invoked whenever the Button, roll, is clicked.
• What happens if we press enter or return while the cursor is in a TextField? Why?