Java code for dealing cards from a deck

Question

I am trying to write a method to remove the specified number of cards from the top of the deck and return them as an array.

This is what i have done so far. A method to create the deck, copy the deck, a method to return the card that is at the specified position in the array, a method to returns the size of the array of Cards, shuffle, and cut the deck (not sure if these are correct). Here is the card class

public class Card {

    private final int suit; // 0, 1, 2, 3 represent Spades, Hearts, Clubs,
                            // Diamonds, respectively

    private final int value; // 1 through 13 (1 is Ace, 11 is jack, 12 is
                                // queen, 13 is king)

    /*
     * Strings for use in toString method and also for identifying card images
     */
    private final static String[] suitNames = { "s", "h", "c", "d" };
    private final static String[] valueNames = { "Unused", "A", "2", "3", "4",
            "5", "6", "7", "8", "9", "10", "J", "Q", "K" };

    /**
     * Standard constructor.
     * 
     * @param value
     *            1 through 13; 1 represents Ace, 2 through 10 for numerical
     *            cards, 11 is Jack, 12 is Queen, 13 is King
     * @param suit
     *            0 through 3; represents Spades, Hearts, Clubs, or Diamonds
     */
    public Card(int value, int suit) {
        if (value < 1 || value > 13) {
            throw new RuntimeException("Illegal card value attempted.  The "
                    + "acceptable range is 1 to 13.  You tried " + value);
        }
        if (suit < 0 || suit > 3) {
            throw new RuntimeException("Illegal suit attempted.  The  "
                    + "acceptable range is 0 to 3.  You tried " + suit);
        }
        this.suit = suit;
        this.value = value;
    }

    /**
     * "Getter" for value of Card.
     * 
     * @return value of card (1-13; 1 for Ace, 2-10 for numerical cards, 11 for
     *         Jack, 12 for Queen, 13 for King)
     */
    public int getValue() {
        return value;
    }

    /**
     * "Getter" for suit of Card.
     * 
     * @return suit of card (0-3; 0 for Spades, 1 for Hearts, 2 for Clubs, 3 for
     *         Diamonds)
     */
    public int getSuit() {
        return suit;
    }

    /**
     * Returns the name of the card as a String. For example, the 2 of hearts
     * would be "2 of h", and the Jack of Spades would be "J of s".
     * 
     * @return string that looks like: value "of" suit
     */
    public String toString() {
        return valueNames[value] + " of " + suitNames[suit];
    }

    /**
     * [STUDENTS SHOULD NOT BE CALLING THIS METHOD!] Used for finding the image
     * corresponding to this Card.
     * 
     * @return path of image file corresponding to this Card.
     */
    public String getImageFileName() {

        String retValue;
        retValue = suitNames[suit];
        if (value <= 10)
            retValue += value;
        else if (value == 11)
            retValue += "j";
        else if (value == 12)
            retValue += "q";
        else if (value == 13)
            retValue += "k";
        else
            retValue += "Unknown!";
        return "images/" + retValue + ".gif";
    }
}

The Deck method is the one that I need help on

public class Deck {

    private Card[] cards;

    public Deck() {
        cards = new Card[52];
        int numberOfCard = 0;
        for (int suit = 0; suit <= 3; suit++) {
            for (int value = 1; value <= 13; value++) {
                cards[numberOfCard] = new Card(value, suit);
                numberOfCard++;
            }
        }
    }

    public Deck(Deck other) {

        cards = new Card[other.cards.length];
        for (int i = 0; i < other.cards.length; i++) {
            cards[i] = other.cards[i];
        }
    }

    public Card getCardAt(int position) {
        if (position >= cards.length) {
            throw new IndexOutOfBoundsException("Values are out of bounds");
        } else {
            return cards[position];
        }
    }

    public int getNumCards() {
        return cards.length;
    }

    public void shuffle() {
        int temp = 0;
        for (int row = 0; row < cards.length; row++) {
            int random = (int) (Math.random() * ((cards.length - row) + 1));
            Deck.this.cards[temp] = this.getCardAt(row);
            cards[row] = cards[random];
            cards[random] = cards[temp];
        }

    }

    public void cut(int position) {
        Deck tempDeck = new Deck();
        int cutNum = tempDeck.getNumCards() / 2;
        for (int i = 0; i < cutNum; i++) {
            tempDeck.cards[i] = this.cards[52 - cutNum + i];
        }
        for (int j = 0; j < 52 - cutNum; j++) {
            tempDeck.cards[j + cutNum] = this.cards[j];
        }
        this.cards = tempDeck.cards;
    }

    public Card[] deal(int numCards) {
        return cards;
    }

}

Answer 1

Provided you can't use Lists, it seems a good idea to have another variable with the index of the deck's top card:

public class Deck {

    private Card[] cards;
    private int topCardIndex;

    public Deck() {
        cards = new Card[52];
        int numberOfCard = 0;
        for(int suit = 0; suit <= 3; suit++){
            for(int value = 1; value <= 13; value++){
                cards[numberOfCard] = new Card(value, suit);
                numberOfCard++;
            }
        }
        topCardIndex = 0;
    }

    public Card getCardAt(int position) {
        if (position >= cards.length - topCardIndex || position < topCardIndex) {
            throw new IndexOutOfBoundsException("Values are out of bounds");
        } else {
            return cards[topCardIndex + position];
        }
    }

    public Card[] deal(int numCards) {
        // FIXME: check bounds, or make method "Card pickCardAt(int position)"
        // that removes the card from the deck
        Card[] drawnCards = new Card[numCards];
        for(int index = 0; index < numCards; index ++) {
            drawnCards[index] = cards[topCard];
            topCard++;
        }
        return drawnCards;
    }

---

I think you'd be better with making the Deck's card collection a List instead of a Card[], so you have nicer operations like remove().

If you want to take the n first cards from the deck, you then simply remove() n times to your resulting array (that I would make a List, too).

public List<Card> deal(int numCards) {
    List<Card> drawnCards = new ArrayList<Card>(numCards);
    for(int index = 0; index < numCards; index++) {
        drawnCards.add(cards.remove(0));
    }
    return drawnCards;
}

Answer 2

This is how I am dealing with a card deck in my game. I also have read() method that reads cards from XML file and pushes them into.

import java.util.Stack;

public class CardStack extends Stack<Card> {

    public CardStack () {}

    public void shuffle() {
        List<Card> list = this.subList(0, this.size());
        //changes in this list are reflected in original Stack
        Collections.shuffle(list);
    }

    public Card pop () {
        try {
            Card card = super.pop();
            return card;
        } catch (EmptyStackException e) {
            return null;
        }
    }
}