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Chapter 5
Black Jack
Chapter Objectives
• Provide a case study example from
problem statement through
implementation
• Demonstrate how a set can be used to
solve a problem
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Black Jack
• Black Jack is a card game typically involving
multiple players and a dealer
• Each card in a hand is awarded points
based upon its face value
• Face cards are worth 10 points each
• Numeric cards are worth their face value
• Aces are worth either 1 or 11 points
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Black Jack
• The goal of the game is to be closer to 21
than the dealer without going over 21
• Black Jack is usually played with a shoe of
cards (a collection of seven decks)
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Black Jack
• For this case study, we define black jack as
a one-player v.s. the dealer interactive card
game
• We will also limit the game to a single deck
of cards rather than a shoe
• The player begins the game by clicking a
Deal button
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Black Jack
• The player and the dealer are then dealt two
cards
• The player can see their own cards and one
card of the dealer
• The player then has the choice to hit (take
another card) or stay (accept this hand as
final for this game)
• If the player busts (goes over 21) then the
game is over
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Black Jack
• Once the player elects to stay, the dealer
then chooses to hit or stay
• The dealer must hit on 16 or less and must
stay otherwise
• An Ace is considered to be 1 point rather
than 11 points if otherwise it would cause the
player or dealer to bust
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Black Jack - Initial Design
• Our black jack game is made up of the
components of the game, the function of the
game, and the user interface
• The components include cards, deck, and
players hands
• The function includes controlling the order of
play, whether a player hits or stays, and the
value of a players hand
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5-8
Black Jack - Initial Design
• In this case study, there is a clear distinction
between the low-level components of the
game and the game itself
• These low-level components (card, deck,
hand) are also very well defined in terms of
state and behavior
• Thus a bottom-up approach to this design
problem makes sense
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5-9
Black Jack - Initial Design
• Bottom-up simply means that we will design
the low-level components first and then work
our way up to the driver
• Other approaches include top-down and reuse based design
• Keep in mind, these are simply frameworks
not rigid models
• Thus we will often find ourselves mixing
these approaches even on the same system
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5-10
Black Jack - the Card Class
• A Card object must represent:
–
–
–
–
the suit of the card (heart, diamond, club, or spade),
the value of the card (1 to 11),
the face of the card (ace, king, queen, six, two, etc.),
the image of the card
• A Card object must also provide a constructor,
operations to:
– retrieve the suit, value, face, or image of the card,
– an operation to change the value of an ace from 11 to 1
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5-11
Black Jack - the Deck Class
• A deck is an unordered collection of unique
cards
• Thus a set is a perfect collection to represent
a deck
• The Deck class must include
– the collection of Cards,
– a method to retrieve a random card from the deck
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Black Jack - the Deck Class
• We will also choose to instantiate a new
deck at the beginning of each new game
• This eliminates the possibility of ever having
an “empty” deck during a game
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Black Jack - the Hand Class
• A hand is a collection of unique cards that have
been dealt to a player
• A Hand object must keep track of:
– the cards in the hand,
– the count of the cards in the hand,
– the value of the hand
• A Hand object must also provide methods to:
–
–
–
–
add a card to the hand,
remove a card from the hand,
return the value of the hand,
provide a string representation of the hand
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Black Jack - the Hand Class
• A Hand object must also provide a method to
determine if an ace is in the hand and needs
to be reduced in value from 11 to 1
• As with a Deck, a set seems a reasonable
collection to represent a Hand since each of
the cards in the Hand are unique and order
does not matter
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Black Jack - the BlackJack Class
• Separating the function of the game from the
user interface, we will have a BlackJack
class to control the game and a
BlackJackGUI class to provide the interface
• The BlackJack class must represent
– the hands of both players
– the deck
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Black Jack - the BlackJack Class
• This class must provide methods to:
•
•
•
•
•
deal the initial cards,
hit a particular player,
return the value of a player’s hand,
determine is a player has busted,
determine the winner of the game
• The BlackJack class will use the Deck class
to store the deck and the Hand class to
represent each player
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Black Jack - the BlackJackGUI
Class
• The BlackJackGUI class will provide the
user interface for our game
• This class will provide:
•
•
•
•
a deal button,
buttons for the player to hit or stay,
a display of each player’s hand
a display of the winner of the game
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FIGURE 5.2
User interface design for BlackJack
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BlackJack - the BlackJackDemo
Class
• The BlackJackDemo class will serve as
the driver for our system
• This class simply creates an instance
of BlackJackGUI and calls its display
method
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FIGURE 5.1
Blackjack
class diagram
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