Question

我正在尝试创建一种处理一副牌的交易方法。

   import java.util.List;
   import java.util.ArrayList;

    /**
     * The Deck class represents a shuffled deck of cards.
     * It provides several operations including
     *      initialize, shuffle, deal, and check if empty.
     */
    public class Deck {

        /**
         * cards contains all the cards in the deck.
         */
        private List<Card> cards;

        /**
         * size is the number of not-yet-dealt cards.
         * Cards are dealt from the top (highest index) down.
         * The next card to be dealt is at size - 1.
         */
        private int size;


        /**
         * Creates a new <code>Deck</code> instance.<BR>
         * It pairs each element of ranks with each element of suits,
         * and produces one of the corresponding card.
         * @param ranks is an array containing all of the card ranks.
         * @param suits is an array containing all of the card suits.
         * @param values is an array containing all of the card point values.
         */
        public Deck(String[] ranks, String[] suits, int[] values) {
            /* *** TO BE IMPLEMENTED IN ACTIVITY 2 *** */

                    cards = new ArrayList<Card>();

                    int n = 0; 
                    for(int i = 0; i < ranks.length - 1; i++)
                        for(int j = 0; j < suits.length - 1; j++)
                            for(int k = 0; k < values.length - 1; k++)
                            {
                                if(n < cards.size())
                                    cards.add(n + 1, new Card(ranks[i],
                                              suits[j], values[k]));   
                            }

                    this.size =  52 - cards.size(); 
                    shuffle(); 
        }


        /**
         * Determines if this deck is empty (no undealt cards).
         * @return true if this deck is empty, false otherwise.
         */
        public boolean isEmpty() {
            /* *** TO BE IMPLEMENTED IN ACTIVITY 2 *** */
                    if(size() == 0)
                        return true;
                    else 
                        return false; 
        }

        /**
         * Accesses the number of undealt cards in this deck.
         * @return the number of undealt cards in this deck.
         */
        public int size() {
            /* *** TO BE IMPLEMENTED IN ACTIVITY 2 *** */
                    return this.size;// the number of undealt cards in the deck 

        }

        /**
         * Randomly permute the given collection of cards
         * and reset the size to represent the entire deck.
         */
        public void shuffle() {
            /* *** TO BE IMPLEMENTED IN ACTIVITY 4 *** */
        }

        /**
         * Deals a card from this deck.
         * @return the card just dealt, or null if all the cards have been
         *         previously dealt.
         */
        public Card deal() {
            /* *** TO BE IMPLEMENTED IN ACTIVITY 2 *** */
                    if(isEmpty())
                        return null; 
                    else
                    {
                        this.size++;
                        return cards.get(size - 1); 
                    } 
        }

        /**
         * Generates and returns a string representation of this deck.
         * @return a string representation of this deck.
         */
        @Override
        public String toString() {
            String rtn = "size = " + size + "\nUndealt cards: \n";

            for (int k = size - 1; k >= 0; k--) {
                rtn = rtn + cards.get(k);
                if (k != 0) {
                    rtn = rtn + ", ";
                }
                if ((size - k) % 2 == 0) {
                    // Insert carriage returns so entire deck is visible on console.
                    rtn = rtn + "\n";
                }
            }

            rtn = rtn + "\nDealt cards: \n";
            for (int k = cards.size() - 1; k >= size; k--) {
                rtn = rtn + cards.get(k);
                if (k != size) {
                    rtn = rtn + ", ";
                }
                if ((k - cards.size()) % 2 == 0) {
                    // Insert carriage returns so entire deck is visible on console.
                    rtn = rtn + "\n";
                }
            }

            rtn = rtn + "\n";
            return rtn;
        }
    ----------

    }

Answer 1

else
    {
        this.size++;
        return cards.get(size - 1); 
    }

看起来对我很怀疑。您似乎正在尝试访问nth数组的n-size元素。

一旦你有了一个大小，你就不能在没有向列表添加新元素的情况下增加它。

Answer 2

这条线看起来很可疑：

this.size =  52 - cards.size();

由你自己的Javadoc：

尺寸是未发牌的数量

所以说在for循环之后，List中有52张牌。您的尺寸设置为52 - 52 = 0，这意味着零牌都不存在，或者更确切地说所有牌都是在做任何事情之前处理的。

this.size应初始化为：

this.size = cards.size();

我还建议将其重命名，因为它不是非常具有描述性，但可能超出了您“允许”做的范围*（它会查看您是否填写了骨架代码）。我会称之为：

private int cardsRemaining;

因为此值是尚未处理卡的数量，您需要在交易时减少。 已发送的数量已经向上， undealt 卡的数量已经向下。

public Card deal() {
    if(isEmpty()) {
        return null;
    } 
    else
    {
        this.size--;
        return cards.get(size - 1); 
    } 
}

_{*众所周知，教育工作者的代码总是100％完美无瑕，在任何情况下都不能被质疑或改进！}

我无法解决indexOutOfBounds错误

2 个答案: