Need some OO design pointers for a Java card game I wrote for uni

Question

Hi,
I hope a few of you Java sifus can help me understand I dilemma I keep finding myself in.
I created a card game for a university assignment which works great but its not very OO at the moment.
I only have 3 classes; a Card class, a Deck class and a Game class which contains all my GUI, AI, Game Controller, Player and Hand code.
The assignment is over but I feel like enhancing the game, adding animation, multiplayer, several AI agents etc.
The first thing I have attempted is animation and I've hit a brick wall. I am trying to create animation for my card game whereby I have an animation showing the cards being shuffled and then an animation which shows the cards being dealt to the players. The game then commences. The cards on the GUI then need to be clickable (MouseListeners?) to play the game. If you're running Windows 7, load up 'Hearts' and you'll know what I'm trying to achieve.
I don't understand how the GUI, and Card class need to be seperated so that its good OO.
If I give you a few snippets of code, it might explain the situation:
A snippet of my card class is as follows:
import javax.swing.*;
public class Card extends JLabel //Each card is a JLabel
     private int value;                    //variable for the value of the card
     private int suit;                         //variable for the suit of the card
     private ImageIcon frontOfCard;     //Displays the image of the front of the cards
     private ImageIcon backOfCard;          //displays the image of the back of the cards
     public Card (int Value, int Suit, ImageIcon front, ImageIcon back)
          value = Value;               
          suit = Suit;               
          frontOfCard = front;     
          backOfCard = back;
          setIcon(backOfCard);     //To make it non-visible when dealt
     }As you can see, each card is a JPanel. I've been told by some I shouldn't extend JPanel but rather that I should have a BufferedImage/Image instance variable for each card as the image of the card. The thing is that I need each card displayed on the GUI which can then be clickable. When it is clicked, it is moved from the players hand, into the players move. - There needs to be an animation showing this.
I've got the animation code figured out in terms of how to move 'images' around a screen to make a pleasing animation. The problem is there are no clickable listeners for images, so the Images needs to be inside some container; a widget which can fire events - Hence the reason I have chosen to extend JPanel for my Cards.
and a Deck class, snippet is as follows:
public class Deck extends JLabel //The deck will be shown on the GUI as a JLabel
     private ArrayList<Card> standardDeck;
     public Deck()
          standardDeck = new ArrayList<Card>();
          ImageIcon cardBack = new ImageIcon("CardBack.png");
          setPreferredSize(new Dimension(90, 135));
          setIcon(cardBack);
          int cardCount = 0;     //This variable counts the cards. Is used to assist in the name generation of the imageicon filename
          String str; //the imageIcon constructor accepts filenames as strings so this string holds the filename of the corresponding card image file.
          for (int a=0; a<4; a++) //putting the cards into the deck with the specifed parameters
               for (int b=2; b<15; b++)
                    cardCount+=1;     //incrementing the card count (the card files are named 1-52 as integers)
                    str = Integer.toString(cardCount); //Integer is converted to string type before being added to string str variable
                    str += ".png"; //To complete the image filename, ".png" has to be concatenated to the string.
                    standardDeck.add(new Card(b, a, new ImageIcon(str), cardBack)); //creating and then adding the cards
     }This is how I envisage a new class diagram for my game:
Card class
Game Class <--- Holds a Deck instance, Players instances, and the GUI instance
Player Class <-- Will contains hand 'instances' , but I will not create a seperate 'Hand' Class, I will use an ArrayList.
AI Class extends Player Class
GUI Class
Deck Class <-- contains 52 cards
My question is, how do I show the Cards on the GUI if my Cards are in a Deck and the Deck is held in the Game class?
Please note that there are 52 cards, so potentially 52 images on the GUI, each of which needs to be clickable. When clicked, the cards are moved about, e.g. from the deck to a players hand, from a players hand back to the deck, from a players hand to a players current move hand.
etc
I've read that GUI, program control, and logic should be seperated. If thats the case, what do I have in my GUI class if the Cards (which are JPanels) are held in the Deck class which in turn is held in the Game class?
Any help on this would be greatly appreciated!
I know what I have written may not be fully clear. I find it hard sometimes to fully convey a problem at hand. Please let me know if you don't understand what I've written and I'll do my best to explain further.

Answer 1

Faz_86 wrote:
Hi,
I hope a few of you Java sifus can help me understand I dilemma I keep finding myself in.
I created a card game for a university assignment which works great but its not very OO at the moment.
I only have 3 classes; a Card class, a Deck class and a Game class which contains all my GUI, AI, Game Controller, Player and Hand code.
The assignment is over but I feel like enhancing the game, adding animation, multiplayer, several AI agents etc.
Admirable, and the best way to learn, doing something that interests you.
The first thing I have attempted is animation and I've hit a brick wall. I am trying to create animation for my card game whereby I have an animation showing the cards being shuffled and then an animation which shows the cards being dealt to the players. The game then commences. The cards on the GUI then need to be clickable (MouseListeners?) to play the game. If you're running Windows 7, load up 'Hearts' and you'll know what I'm trying to achieve.
I don't understand how the GUI, and Card class need to be seperated so that its good OO.
If I give you a few snippets of code, it might explain the situation:
A snippet of my card class is as follows:
Do a quick Google on the model view controller pattern. Your listeners are your controllers. Your JPanel, JButton, etc. are your view. The AI, Player, Card and Deck (and presumably something like Score) are your model. Your model should be completely testable and not dependent on either the controller or the view. Imagine you could play the game from the command line. Get that working first. Then you can add all the bells and whistles for the UI.
import javax.swing.*;
public class Card extends JLabel //Each card is a JLabel
(redacted)
As you can see, each card is a JPanel. I've been told by some I shouldn't extend JPanel but rather that I should have a BufferedImage/Image instance variable for each card as the image of the card. The thing is that I need each card displayed on the GUI which can then be clickable. When it is clicked, it is moved from the players hand, into the players move. - There needs to be an animation showing this.Extending JPanel is fine. As you noted, you need something to add listeners to. However, I would separate things a bit. First, a card really only has a rank and suit (and perhaps an association to either the deck or a player holding the card). The notion of setIcon() is where you are tripping up. The card itself exists in memory. You should be able to test a card without using a UI. Create a separate class (CardPanel or something similar) that has a reference to a Card and the additional methods needed for your UI.
I've got the animation code figured out in terms of how to move 'images' around a screen to make a pleasing animation. The problem is there are no clickable listeners for images, so the Images needs to be inside some container; a widget which can fire events - Hence the reason I have chosen to extend JPanel for my Cards.
and a Deck class, snippet is as follows:
public class Deck extends JLabel //The deck will be shown on the GUI as a JLabel
     private ArrayList<Card> standardDeck;
     public Deck()
          standardDeck = new ArrayList<Card>();
          ImageIcon cardBack = new ImageIcon("CardBack.png");
          setPreferredSize(new Dimension(90, 135));
          setIcon(cardBack);
          int cardCount = 0;     //This variable counts the cards. Is used to assist in the name generation of the imageicon filename
          String str; //the imageIcon constructor accepts filenames as strings so this string holds the filename of the corresponding card image file.
          for (int a=0; a<4; a++) //putting the cards into the deck with the specifed parameters
               for (int b=2; b<15; b++)
                    cardCount+=1;     //incrementing the card count (the card files are named 1-52 as integers)
                    str = Integer.toString(cardCount); //Integer is converted to string type before being added to string str variable
                    str += ".png"; //To complete the image filename, ".png" has to be concatenated to the string.
                    standardDeck.add(new Card(b, a, new ImageIcon(str), cardBack)); //creating and then adding the cards
     }This is how I envisage a new class diagram for my game:
I am not an animation buff, so I will assume the above works.
Card classRemove the UI aspects to this class, and I think you are all set here.
Game Class <--- Holds a Deck instance, Players instances, and the GUI instancePresumably this is where main() resides. It will certainly have a reference to model classes (player, game, deck, etc.) and likely the master JFrame (or a controller class you create yourself).
Player Class <-- Will contains hand 'instances' , but I will not create a seperate 'Hand' Class, I will use an ArrayList.Does a player really have multiple hands? It seems to me more of a one-to-one relationship (or a player has a one-to-many relationship to Card).
AI Class extends Player ClassWhy extend Player? Create a Player interface, then have a HumanPlayer and AIPlayer implementation. Common parts could be refactored out into either a helper class (delegation) or AbstractPlayer (inheritance).
GUI ClassMy assumption is that this class has a reference to the master JFrame.
Deck Class <-- contains 52 cards
Yes. You may end up recycling this class such that a Deck can also function as a Hand for a given player. If there are differences between the two, create an interface and have a Hand and a Deck implementation. Coding to interfaces is a good thing.
My question is, how do I show the Cards on the GUI if my Cards are in a Deck and the Deck is held in the Game class?You need to pass a reference to the appropriate view class. That is how MVC works. The controller receives a request from the view, dispatches to some model functionality you write (such as GameRulesEngine, Deck, etc.) and returns a result to the view (which could be the same view or a different one, imagine someone clicking 'high scores').
Please note that there are 52 cards, so potentially 52 images on the GUI, each of which needs to be clickable. When clicked, the cards are moved about, e.g. from the deck to a players hand, from a players hand back to the deck, from a players hand to a players current move hand.
etc
That is up to you to write the animation code. In principle, you have a mouse listener, and then you take the appropriate rendering steps.
I've read that GUI, program control, and logic should be seperated. If thats the case, what do I have in my GUI class if the Cards (which are JPanels) are held in the Deck class which in turn is held in the Game class?
See above.
Any help on this would be greatly appreciated!
You are welcome.
I know what I have written may not be fully clear. I find it hard sometimes to fully convey a problem at hand. Please let me know if you don't understand what I've written and I'll do my best to explain further.No, you have been doing fine.
- Saish