Graphical BlackJack Adding Features
Introduction
These final series of articles on Graphical Blackjack are written in near real time. I am reremebering some Java Graphics programming. I am sharing the design choices and reporting on the mistakes I make along the way. Since the target audience is the Novice programmer it's important for the Novice to see how new ground is broken in the Software Development. Most books walk you down the path of perfect design and implementation for their coding examples. While good design and documentation is important it assumes perfect knowledge in how an API works. If you are just learning how an API functions you can still be productive. The Novice programmer should not be afraid to fly by the seat of their pants. I hope seeing how design decisions affect a program and how easy it is to rip up code and reimplement will give you the courage to experiment on your own.
In this Graphics investigation another programming skill being displayed is the adaptation of code for a new purpose. In a commercial Blackjack Game the PlayingCard object might have to be designed as a completely new kind of object just to get that professional Vegas game look. As you will learn (if the ultimate goal is getting functional rapidly) we can adapt existing Java objects to do our bidding and a functional Graphics program can be put together quickly.
Without much introduction in the text below I introduce a very high level concept of Design Patterns. The subject matter of Design Patterns has been blogged about be Developers for a long time. I provide a source reference but the subject is something the reader needs to investigate further.
Problems with JFrame
The first try at adding graphics to the blackjack program dealt with getting a window to open and getting a card picture to display. Now the rest of the PlayingCards in CardDeck need to be displayed. Rather than turning CardDeck into a Graphics object, just add a call to place all the PlayingCards it has in the PlayingCard array into the JFrame.
/** * test routine to see how all the cards are displayed from the CardDeck * CardDeck is not a Graphics object itself but a container for the * Graphics object PlayingCard. * @param f JFrame to add cards to */ public void addPlayingCardsToFrame(JFrame f) { for (PlayingCard c : deck) { f.add(c); } }
Add the following line to the "run" method in the BlackJack class
- this.card.addPlayingCardsToFrame(frame);
So the graphics method calls (in BlackJack.run()) now look like this:
JFrame frame = new JFrame("BlackJack"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setPreferredSize(new Dimension(300,300)); PlayingCard p1 = new PlayingCard(2,2); frame.getContentPane().add(p1); this.card.addPlayingCardsToFrame(frame); frame.pack(); frame.setVisible(true);
When the program is executed the following window get's displayed:
- What happened to the 3 of diamonds displayed before?
- Where are all the rest of the playing cards added to the frame?
- Why did it jump to the King of diamonds and just display that?
52 Card Pile Up
It turns out that they all got displayed! but, in the exact same place. Leaving the last card to be displayed as the only one visible. This is not the functionality I was hoping for. I was looking for the cards to be equally spaced in the JFrame for all to see
The problem stems from the fact that JFrame (in its current default state) doesn't know how to place my current implementation of PlayingCard. It ends up calling PlayingCard's paint method (at some point) but that method always starts it's painting at 0,0.
The Java Swing API has "manager" objects that tell the JFrame how to place the objects that have been added to the frame. These are "Layout" managers and they properly space objects based on various algorithms developed for displaying objects in a window.
Content Pane
The JFrame, according to the tutorials at the Oracle Website has a ContentPane that is already using the default layout manager FlowLayout. What the FlowLayout manager does is space objects out appropriately from left to right using the space available to determine how many cards to place horizontally and then it continues to place them vertically as rows of the same size until it runs out of JFrame space. To see all the objects at once the user must resize the JFrame with the mouse allowing more horizontal and vertical room. When this happens the FlowLayout Manager is supposed to redisplay the objects in the space available. The objects "Flow" into the amount of space.
This is not happening to the PlayingCard class. While we could delve deeper into the Graphics2D library and try to make this low level graphics API work appropriately the question comes up, why bother? From glancing at the Tutorials at the Oracle site things like JLabel and JButton get placed on the screen properly with the FlowLayout manager. Taking the high road the card image just has to extend one of these types and it should get placed properly (if the tutorials are to be believed).
JLabel
The following Tutorial at
has just the functionality this project needs. By creating a JLabel object that displays an Icon, maybe we can trick the JFrame into displaying all the cards just by inheriting from the JLabel object.
JLabel is usually used to present text labels next to text boxes (JTextField class) used for user input. The combination of the two objects is the way to present a Graphical Form to be filled out by the user. The Developers behind the Swing API ingeniously decided that a picture is as good as text for a JLabel. After reading through the Tutorial I came up with this implementation to try:
- Change the CardImageFactory to produce "ImageIcon" objects (after all I had originally taken this out).
- Change the PlayingCard class to inherit (ie. extend) from the JLabel class and modify its constructor to store the image
- Adjust the testing method in CardDeck to add all the cards to the Content Pane from the JFrame object
- Make the call to the CardDeck method in the "run" method of the BlackJack class
CardImageFactory
After renaming the Factory method call in CardImageFactory the code looks very close to the original from example posted on stackoverflow.com.
public static ImageIcon makeCardIcon(int rank, int suit) { int x = (rank * width) / PlayingCard.RANK; int y = (suit * height) / PlayingCard.SUIT; int w = width / PlayingCard.RANK; int h = height / PlayingCard.SUIT; //return fullDeckImg.getSubimage(x, y, w, h); BufferedImage cardImg = fullDeckImg.getSubimage(x, y, w, h); return new ImageIcon(cardImg); }
PlayingCard
Having PlayingCard "extend" JLabel the class inherits the "setIcon" method from JLabel. Using the ImageIcon created from the factory call makeCardIcon there is nothing more that needs to be done. Crazy right. All that work with Graphics2D before was unnecessary. Just place the ImageIcon into the appropriate field in the super class and FlowLayout manager will find it and display it within the JFrame. That's the beauty of Object Oriented. Small changes can have awesome effects.
/* * PlayingCard.java - Playing card class for BlackJack */ package blackjack; import javax.swing.JLabel; /** * Object model of a simple playing card. Class has been adapted to be displayed * in a JFrame * * @author Nasty Old Dog */ public class PlayingCard extends JLabel{ public static final int RANK=13; public static final int SUIT=4; private int cardno; private int score = 0; private String faceVal = "A23456789TJQK"; private String suit = "CSHD"; public PlayingCard(int cardno, int score) { this.cardno = cardno; this.score = score; this.setIcon(CardImageFactory.makeCardIcon(cardno%RANK, cardno%SUIT)); } /** * Get the card scoring value for blackjack face cards = 10 ace = 11 * all other cards equal their face value. Aces can equal 1 at times and * is handled elsewhere * @return */ public int card_value() { return this.score; } /** * convert cardno into text string of face value and suit * @return */ public String getCardText() { int card_val = this.cardno % 13; int card_suit = this.cardno % 4; return this.faceVal.substring(card_val, card_val + 1) + this.suit.substring(card_suit, card_suit + 1); } /* * paint the image for the Playing card as Graphics2D image * @param _g @Override public void paint(Graphics _g) { Graphics2D g = (Graphics2D) _g; g.drawImage(img,5*this.cardno%13,5*this.cardno%4,this); } * */ }
The paint method is all commented out. All the work is now done with two lines in the above code
- public class PlayingCard extends JLabel{
- this.setIcon(CardImageFactory.makeCardIcon(cardno%RANK, cardno%SUIT));
CardDeck
CardDeck will not need to be turned into a graphics object. But it does act as a container for graphics objects (remember PlayingCards is now a JLabel). So to assist in testing this program a method has been added "addPlayingCardsToFrame". You would think the parameter for this class should be a JFrame. But there are other objects that provide "ContentPane"s so a more general parent class has been used "Container". Testing may be extended to include those Swing objects (other than JFrame) so why not use the more general case.
/** * test routine to see how all the cards are displayed from the CardDeck * CardDeck is not a Graphics object itself but a container for the * Graphics object PlayingCard. * @param p ContentPane (for now from JFrame) to add cards to */ public void addPlayingCardsToFrame(Container p) { for (PlayingCard c : deck) { p.add(c); } }
Design Patterns
There is one more change to CardDeck that has nothing to do with Graphics but it has been something that's been bothering me about the design of the code ever since it was changed into Object Oriented code. The Blackjack score value was hard coded into multiple classes because I was too lazy to decide how to best represent the functionality and at what level it should be placed.
There is no one right answer but my thinking was that a PlayingCard is a playing card, meaning in real life it is plastic coated piece of paper with pictures on it. It has no real notion of where the value comes from. That value comes from the type of game that is being played. It would be nice to move the game specific details out of PlayingCard, CardDeck, and Hand. Right? because if you needed PlayingCards that knew how to play BlackJack they should be called BlackJackPlayingCards and not PlayingCards implying some general usability.
For the next leap in your development as a Software Engineer/Computer Scientist you should get, read, and try to understand the book "Design Patterns" by the "Gang of Four". Once Object Oriented programming became established it was found to be an expressive platform to capture Higher Level concepts. While the code examples in the original book are written in C++ many authors have followed the Gang of Four and implemented examples in almost every language imaginable. The book codifies many things programmers used to have to work for a couple of years in industry to learn.
Strategy Pattern
So the strategy pattern looks like it will work. Since I don't plan on implementing different strategies at the present moment I'm not going to create a Strategy Interface that the Strategy Class should implement. Instead just a singlen BlackJackStrategy class will be used without the full hierarchy shown in the book.
BlackJackStrategy Class
The BlackJackStrategy Class is the final resting ground of the cardscore array. It will have a method call to return the BlackJack score of a card encapsulating the use of the card score array. The other method "getScore" takes a hand parameter and implements the scoring algorithm that used to be in the Hand object. The Hand sort method stays with the Hand class and returns an ArrayList of PlayingCards that are used to score the hand. This effectively isolates game specific information to one class. If you were to design a whole suite of card games you would extend this pattern to encompass the game logic of the other games.
/* * BlackJackStrategy.java */ package blackjack; import java.util.ArrayList; /** * This is a Strategy Design Pattern roughly implemented as Cataloged in * the book Design Patterns by the Gang of Four. Hands and CardDecks are * rather neutral objects. The stuff that makes a game Blackjack should be * in a separate class that gets passed to the CardDeck and Hand objects when * their constructor is called. In essence making a BlackJack Hand or BlackJack * CardDeck. This will pull all the card value arrays and scoring to a central * class. The biggest difference is that this class should be abstracted * so that classes like CardDeck and Hand don't need to specify a particular * Strategy. The idea is to keep them agnostic and let the upper levels of the * program decide what kind of strategy will be imposed. For now however the * class is being used to separate out the card_score array and the scoring * algorithm for hands. The ultimate goal would be to create a card game * platform where you only have to modify the strategy to create a new type * of card game. * * @author Nasty Old Dog */ public class BlackJackStrategy { private int card_score[] = {11, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 10, 10}; public final static int RANK = 13; BlackJackStrategy() { super(); } /** * Take an internal int cardno representation and return it's blackjack * value * @param cardno an integer between 0 and 51 that represents a specific card * @return the blackjack scoring value of the card */ public int getCardScore(int cardno) { return this.card_score[cardno%RANK]; } /** * determine the score of a blackjack hand, sort the hand then figure out * which Aces should be 1 or 11. * @param h the Hand class passed in * @return returns the score of the hand */ public int getScore(Hand h) { ArrayList<PlayingCard> sorted = h.sortHand(); int score = 0; for (PlayingCard i : sorted) { // Need to test each card to see if it is an ACE // If an ACE and score is < 11 use 11 as ACE value otherwise use 1 // I haven't done a proof but I believe that checking the score // less than 11 is sufficient to handle ACEs and you won't bust a // hand incorrectly if (i.card_value() == 11) { // Processing ACE if (score >= 11) { // ACEs must all be 1 score += 1; } else { score += 11; } } else { // Just add card_value it's not an ACE score += i.card_value(); } } return score; } }
Then the CardDeck Constructor needs a BlackJackStrategy parameter to set the score of the PlayingCards created.
public CardDeck(BlackJackStrategy strategy) { for (int i = 0; i < 52; i++) { deck[i] = new PlayingCard(i, strategy.getCardScore(i)); } }
The Hand Class needs a little rework to have the sort method return an ArrayList rather than use an internal field variable. The constructors need to be modified to create a Strategy field. By overloading the Constructors no changes to the Hand calls do not have to be changed in BlackJack
/* * Hand.java * */ package blackjack; import java.util.ArrayList; /** * models a hand of cards as one would expect in any card game. * * @author Nasty Old Dog */ public class Hand { ArrayList<PlayingCard> cards = new ArrayList<PlayingCard>(); // ArrayList<PlayingCard> sorted = new ArrayList<PlayingCard>(); private String displayName = "change in constructor"; private BlackJackStrategy strategy = null; public Hand() { this.displayName = "Hand"; this.strategy = new BlackJackStrategy(); } public Hand(String displayName) { this.displayName = displayName; this.strategy = new BlackJackStrategy(); } public Hand(String displayName, BlackJackStrategy strategy) { this.displayName = displayName; this.strategy = strategy; } public void deal(CardDeck deck) { this.cards.add(deck.deal()); } public ArrayList<PlayingCard> sortHand() { // sort hand make Aces 11 for sorting purposes // Use the insertion sort code and modify it by using the card_value // method as the way to sort ArrayList<PlayingCard> sorted = (ArrayList<PlayingCard>) this.cards.clone(); // The clone statement does a deep copy of the array list // Just to prove it I print out the sorted field individually // If you had to copy individually (like for the AP) the code would // follow the structure below System.out.print("Cloned: "); for (PlayingCard i : sorted) System.out.print(i.getCardText() + " "); System.out.print("Size: " + sorted.size()); System.out.println(); PlayingCard tmp; for (int i = 1; i < sorted.size(); i++) { for (int j = i; j > 0 && sorted.get(j).card_value() < sorted.get(j-1).card_value(); j--) { // swap values tmp = sorted.get(j); sorted.set(j, sorted.get(j - 1)); sorted.set(j - 1, tmp); } } return sorted; } public int scoreHand() { return this.strategy.getScore(this); } public void display() { System.out.println(this.displayName); for (PlayingCard i : cards) { System.out.print(i.getCardText() + " "); } System.out.println(); } }
Final Touches
Last but not least Java Swing API method calls need to be added to the BlackJack run method:
//SwingUtilities.invokeLater(new Runnable() { // public void run() { JFrame frame = new JFrame("BlackJack"); Container contentPane = frame.getContentPane(); // Set the layout manager for the JFrame using the contentPaine FlowLayout layout = new FlowLayout(); contentPane.setLayout(layout); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setPreferredSize(new Dimension(300,300)); PlayingCard p1 = new PlayingCard(2,2); contentPane.add(p1); this.card.addPlayingCardsToFrame(contentPane); frame.pack(); frame.setVisible(true); // } //});
The calls that are commented out are reminders that I am not using the Swing API in the standard way. If you think for a moment how are all the mouse clicks going to be handled and what if we had a multiplayer game? The Swing API is meant to run in a separate thread of control and most of the examples on the The Java Tutorial site use this way of starting up the Swing API calls. I may or may not need this ultimately but I thought I would include it as a reminder it may become necessary.
References
- The Java Tutorials "How to Use Icons" The Java Tutorials: How to Use Icons
- Gamma, Erich, Richard Helm, Ralph Johnson, and John Vlissides. "Design Patterns: Elements of Reusable Object-oriented Software". Reading, MA: Addison-Wesley, 1995. Print.
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