java - 尝试打印桥牌游戏时出现空错误

Question

当我运行 main 时，我在这一行收到 java null 错误

int rank = cards[i].getRank();

int points = cards[i].getPoints();

我只是想获取手牌数组中卡片的 countHighCardPoints() 点值，并将这些点添加到总和中。如果我没有在 char suit = cards[i].getSuit(); 上也得到空值，我还将假设我的 countDistributionPoints() 会起作用。

因此我的Hand类(class)需要帮助。

public class Hand
{

 //Holds an array of card objects
 private Card [] cards = new Card [13];

/**
 * Constructor takes array of Cards and assigns that parameter to
 * the instance variable
 */
public Hand(Card [] cards)
{
    Card [] hand = cards;
}

/**
 * Looks through each card in hand array and adds its points
 * if the card has any to a sum highPoints
 */
public int countHighCardPoints()
{
    int highPoints = 0;

    for (int i = 0; i < cards.length; i++) {

        int rank = cards[i].getRank();
        int points = cards[i].getPoints();

       highPoints += points;

    }

    return highPoints;
}


public int countDistributionPoints()
{
    int countPoints = 0;

    for (int i = 0; i < cards.length; i++) {
        //char suit = cards[i].getSuit();

        if (cards[i].getSuit() >= 3)
            countPoints = 0;
        else if (cards[i].getSuit() == 2)
            countPoints++;
        else if (cards[i].getSuit() == 1)
            countPoints += 2;
        else if (cards[i].getSuit() == 0)
            countPoints += 3;
    }

    return countPoints;
}

甲板等级供引用

public class Deck
{
//Holds an array of card objects
private Card [] cards  = new Card [52];

//Holds number of cards remaining in deck
private int count;


/**
 * Creates a Card [] arrayOfCards which is 13 cards for each player 
 * and will determine number of cards that was dealt with count.
 */
public Card [] dealThirteenCards()
{
    Card [] arrayOfCards = new Card [13];

    for (int i = 0; i <= 12 && count < 52; i++) {
        arrayOfCards[i] = cards[i];
        count++;
    }

    return arrayOfCards;
}

Answer 1

仍在研究您的代码，但目前我已经在这里确定了一些内容:

1.在你的 Hand 的构造中，你永远不会将传入的值分配给它的实例变量卡，这就是为什么每个 Hand 下的牌组将是一个空数组的原因。您应该将其更改为:

public Hand(Card [] cards) {
    this.cards = cards;
}

2.Deck下的dealThirteenCards行为异常。

for (int i = 0; i <= 13 && count < 52; i++) {
    arrayOfCards[i] = cards[i];
    count++;
}

初始化 Deck 后，计数将为 -1。上面的代码将为 4 个玩家执行 4 次，每次为每个玩家分配 14 张牌。 如果正确结束，计数将为 -1 + 4*14 = 55，大于 52。因此，您的 for 循环将比预期更早终止。这表明你的游戏中的第四位玩家不会获得我认为的最后三张牌。

希望这有帮助。