Java 二十一点计划

Question

所以我根据您的建议 (Todd Hopp) 重写了它，并更新了 BlackJack class 中 (*) 部分中的 post 这样您就可以看到我是怎么做的现在，但我仍然遇到相同的错误，并且由于某种原因它没有打印 computePlayerValue....

错误：线程 "main" java.lang.NumberFormatException 中的异常：对于输入字符串："King" 在 java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)

at java.lang.Integer.parseInt(Integer.java:580)
at java.lang.Integer.parseInt(Integer.java:615)
at BlackJack.dealCards(BlackJack.java:25)
at PlayCardGame.main(PlayCardGame.java:9)

P.S。我试图在书中查找但找不到答案...BlackJack class 是本书前一章的部分源代码，我不知道它是否是必须有 super();在构造函数那里？我认为只有在父 class 构造函数有参数时才需要这样做？关于它是否必须存在以及它在做什么的任何帮助。

二十一点Class

 public class BlackJack extends CardGameFP{
    int computePlayerValue;
    int computeDealerValue;
    int cardValue;

    public BlackJack() {
        **super();**
        player1 = 2;
        player2 = 2;
    }

    public void display() {
        System.out.println("BlackJack");
    }
//************************************************************* 
    public int getCardValue(Card card) {
    final String rank = card.getRank();
    switch (rank) {
        case "Ace":
            return 1;
        case "King":
        case "Queen":
        case "Jack":
            return 10;
        default:
            return Integer.parseInt(rank);
    }
}

public void dealCards() {
    //Player 1
    System.out.println("Player 1:");
    for(int x = 0; x < playerHand; x++) {
        shuffle();
        System.out.println(fullDeck[x].getRank() + " of " + fullDeck[x].getSuit());
    }
    cardValue1 = getCardValue(fullDeck[0]);
    cardValue2 = getCardValue(fullDeck[1]);
    computePlayerValue = cardValue1 + cardValue2;
    System.out.println(computePlayerValue);
}

//*************************************************************


        //Dealer hand
        System.out.println("\nPlayer 2:");
        for(int x = 0; x < player2; x++) {
            System.out.println(fullDeck[x].getRank() + " of " + fullDeck[x].getSuit() );
            shuffle();
        }
    }
    }


public class Card {

protected String suit;
protected int value;
protected String rank;
protected final int LOW_VALUE = 1;
protected final int HIGH_VALUE = 13;


public String getRank() {
    return rank;
}

public int getValue() {
    return value;
}

public String getSuit() { 
    return suit;
}

public void setSuit(String st) {
    suit = st;
}

public void setValue(int val) {
    if(val >= LOW_VALUE && val <= HIGH_VALUE) {
        value = val;
    }
    else {
        value = LOW_VALUE;
    }
    if(val == 1) {
        rank = "Ace";
    }
    else if(val == 11) {
        rank = "Jack";
    }
    else if(val == 12) {
        rank = "Queen";
    }
    else if(val == 13) {
        rank = "King";
    }
    else {
        rank = Integer.toString(value);
    }           
}   
}

卡牌游戏Class

abstract public class CardGameFP {

int suitNum = 1;
int val = 1;
int player1;
int player2;
protected final int DECK_OF_CARDS = 52;
Card fullDeck[] = new Card[DECK_OF_CARDS];
protected final int LOW_VALUE = 1;
protected final int HIGH_VALUE = 13;
protected final int HIGH_SUIT = 4;
protected final int CARDS_IN_SUIT = 13;

public abstract void display();
public abstract void dealCards();

public CardGameFP() {
    for(int i = 0; i < fullDeck.length; i++) {
        fullDeck[i] = new Card();
        if(suitNum == 1) {
            fullDeck[i].setSuit("Spades");
        }
        else if(suitNum == 2) {
            fullDeck[i].setSuit("Hearts");
        }
        else if(suitNum == 3) {
            fullDeck[i].setSuit("Diamonds");
        }
        else {
            fullDeck[i].setSuit("Clubs");
        }
        fullDeck[i].setValue(val);
        val++;
        if(val > HIGH_VALUE) {
            suitNum++;
            val = 1;
        }            
    }//end for
}   
public void shuffle() {
    for(int firstCard = 0; firstCard < DECK_OF_CARDS; firstCard++ ) {
        firstCard = ((int)(Math.random() * 500) % DECK_OF_CARDS);
        int secondCard = ((int)(Math.random() * 500) % DECK_OF_CARDS);
        Card temp = fullDeck[firstCard];
        fullDeck[firstCard] = fullDeck[secondCard];
        fullDeck[secondCard] = temp;
    }
}
}

PlayCardGameClass

PlayerCardGame

    public class PlayCardGame {

    public static void main(String[] args) {
        Card CG = new Card();
        BlackJack BJ = new BlackJack();

        BJ.display();
        BJ.dealCards();
    }
    }

Answer 1

代替这一行：

cardValue = Integer.parseInt(fullDeck[0].getRank());

我建议你创建一个getCardValue(Card)方法：

public int getCardValue(Card card) {
    final String rank = card.getRank();
    switch (rank) {
        case "Ace":
            return 1;
        case "King":
        case "Queen":
        case "Jack":
            return 10;
        default:
            return Integer.parseInt(rank);
    }
}

然后使用：

cardValue = getCardValue(fullDeck[0]);

编辑：按照@WorldSEnder 的建议，您可以定义一个Rank 枚举：

public enum Rank {
    ACE("Ace", 1),
    TWO("2", 2),
    ...
    QUEEN("Queen", 10),
    KING("King", 10);

    private final String displayName;
    private final int value;

    protected Rank(String displayName, int value) {
        this.displayName = displayName;
        this.value = value;
    }

    public String displayName() {
        return displayName;
    }

    public int value() {
        return value;
    }
}

然后您可以修改 Card 以使用 Rank 而不是 String 作为排名并使用：

cardValue = fullDeck[0].getRank().value();

Answer 2

当你打电话时：

 cardValue = Integer.parseInt(fullDeck[0].getRank());

方法 Interger.parseInt() 正在尝试从 string 中读取 int。问题是有些卡片的等级本身不是字符串，例如 King。所以当你return那张卡的段位时，parseInt()不知道如何处理King。您应该改为使用 fullDeck[0].getVaule() 获取卡片的实际值并解析它。它将是一个介于 1 和 13 之间的字符串。

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