难以从Java中的另一个类调用ArrayLists和Methods

Question

第一次海报,长期潜伏者.

我是第二年计算机科学专业学生,试图编写一个二十一点游戏.这不是一个家庭作业,它只是一个有趣的项目.它没有这样做,所以游戏本身还没准备好,所以请忽略该部分.我花了大约两个小时搜索SO以获得答案,但无法将其他用户的类似问题与我自己的问题进行比较,因此我决定发布我的问题.

我的问题是'deck'ArrayList.从我的Blackjack.java文件中,无论我做什么,我都无法调用它,我无法调用我的Card类中的任何方法,我无法操纵它,我似乎无法做任何事情而不会收到某种错误.

public class Blackjack {
    public int bet;
    public int earnings = 0;
    public int total = 100;
    public boolean inputNeeded = true;

    public Blackjack() {
        Scanner s = new Scanner(System.in);

        System.out.println("               Welcome to Blackjack.");
        System.out.println("             Enter any key to continue.");
        System.out.println("         Otherwise, please type Exit to quit.");

        while (!s.nextLine().toString().toLowerCase().equals("exit")) //Main Game Loop - Only ends when user types Exit.
        {
            while (inputNeeded) {
                System.out.println("You currently have $" + total + ".");
                System.out.print("Please place your bets now. (Min $10): $");

                if (s.hasNextInt()) {
                    bet = s.nextInt();
                    String betString = String.valueOf(bet);
                    inputNeeded = false;

                    if (bet < 10 || bet % 5 != 0) {
                        System.out.println("Your bet is not valid. Your bet must be a minimum of $10 and be a factor of 5.");
                        System.out.println("");
                        inputNeeded = true;
                    }
                } else {
                    System.out.println("Your bet is not valid. Your bet must be a minimum of $10 and be a factor of 5.");
                    System.out.println("");
                }
            }
            inputNeeded = true; 

            /*
             * RESERVED SPACE (stuff to-do)
             * 
             * Deal two cards to dealer and player.
             * Flip cards, add totals
             * If dealer has ace, prompt user if he wants insurance incase dealer blacjack
             * Main loop, as long as neither player has blackjack, prompt user to hit, stay, double down etc.
             * Once loop exits, calculate bets, add into totals. 
             * Increase count of how many games it's been, shuffle the decks at X games depending on howManyDecks (card.java)
             * 
             * RESERVED SPACE (stuff to-do)
             * 
             */
            deck.shuffle();

            break; //until game is finished
        }

        System.out.print("Thank you for playing!");
    }

    public static void main(String[] args) {
        Blackjack game = new Blackjack();
    }
}

和卡类(我知道我可以在循环中完成52张卡,但为了简单起见,我决定不这样做).从我读到的,如果我不想制作静态方法,我必须制作'getter'方法.我不太确定返回方法如何帮助我,比如说,从二十一点类中洗牌,或者从二十一点类中抽取牌(尚未实现),因为这些方法的返回类型将无效.我甚至不确定我的getter方法是否正确,因为我从未试图"获取"之前构造函数所需的参数.

public class Card
    extends Blackjack //Do I need to extend this? <---- not sure
{
    public String name;
    public int value;
    public String suit;
    public int howManyDecks = 8; //most casino's use 8 decks for blackjack

    public Card(String n, int v, String s) {
        name = n;
        value = v;
        suit = s;

        ArrayList<Card> discard = new ArrayList<Card>(); //this will be for any card that is not currently in the deck, I could have called it 'temp'
        ArrayList<Card> deck = new ArrayList<Card>(howManyDecks * 52);

        for (int i = 0; i < howManyDecks; i++) {
            deck.add(new Card("Ace", 1, "Hearts"));
            deck.add(new Card("2", 2, "Hearts"));
            deck.add(new Card("3", 3, "Hearts"));
            deck.add(new Card("4", 4, "Hearts"));
            deck.add(new Card("5", 5, "Hearts"));
            deck.add(new Card("6", 6, "Hearts"));
            deck.add(new Card("7", 7, "Hearts"));
            deck.add(new Card("8", 8, "Hearts"));
            deck.add(new Card("9", 9, "Hearts"));
            deck.add(new Card("10", 10, "Hearts"));
            deck.add(new Card("Jack", 10, "Hearts"));
            deck.add(new Card("Queen", 10, "Hearts"));
            deck.add(new Card("King", 10, "Hearts"));
            deck.add(new Card("Ace", 1, "Spades"));
            deck.add(new Card("2", 2, "Spades"));
            deck.add(new Card("3", 3, "Spades"));
            deck.add(new Card("4", 4, "Spades"));
            deck.add(new Card("5", 5, "Spades"));
            deck.add(new Card("6", 6, "Spades"));
            deck.add(new Card("7", 7, "Spades"));
            deck.add(new Card("8", 8, "Spades"));
            deck.add(new Card("9", 9, "Spades"));
            deck.add(new Card("10", 10, "Spades"));
            deck.add(new Card("Jack", 10, "Spades"));
            deck.add(new Card("Queen", 10, "Spades"));
            deck.add(new Card("King", 10, "Spades"));
            deck.add(new Card("Ace", 1, "Diamonds"));
            deck.add(new Card("2", 2, "Diamonds"));
            deck.add(new Card("3", 3, "Diamonds"));
            deck.add(new Card("4", 4, "Diamonds"));
            deck.add(new Card("5", 5, "Diamonds"));
            deck.add(new Card("6", 6, "Diamonds"));
            deck.add(new Card("7", 7, "Diamonds"));
            deck.add(new Card("8", 8, "Diamonds"));
            deck.add(new Card("9", 9, "Diamonds"));
            deck.add(new Card("10", 10, "Diamonds"));
            deck.add(new Card("Jack", 10, "Diamonds"));
            deck.add(new Card("Queen", 10, "Diamonds"));
            deck.add(new Card("King", 10, "Diamonds"));
            deck.add(new Card("Ace", 1, "Clubs"));
            deck.add(new Card("2", 2, "Clubs"));
            deck.add(new Card("3", 3, "Clubs"));
            deck.add(new Card("4", 4, "Clubs"));
            deck.add(new Card("5", 5, "Clubs"));
            deck.add(new Card("6", 6, "Clubs"));
            deck.add(new Card("7", 7, "Clubs"));
            deck.add(new Card("8", 8, "Clubs"));
            deck.add(new Card("9", 9, "Clubs"));
            deck.add(new Card("10", 10, "Clubs"));
            deck.add(new Card("Jack", 10, "Clubs"));
            deck.add(new Card("Queen", 10, "Clubs"));
            deck.add(new Card("King", 10, "Clubs"));
        }
    }

    public void shuffle() {
        ArrayList<Card> temp = new ArrayList<Card>();
        while (!deck.isEmpty()) {
            int loc = (int) (Math.random() * deck.size());
            temp.add(deck.get(loc));
            deck.remove(loc);
        }
        deck = temp;
    }

    public Card getDeck() {
        return deck;
    }

    public Sting getCardName(int arrayIndex) {
        return deck(arrayIndex, Name);
    }

    public int getCardValue(int arrayIndex) {
        return deck(arrayIndex, Value);
    }

    public String getCardSuit(arrayIndex, Suit);
    {
        return deck(arrayIndex, Suit);
    }
}

尝试运行:

Exception in thread "main" java.lang.Error: Unresolved compilation problem: 
    deck cannot be resolved

    at Blackjack.<init>(Blackjack.java:61)
    at Blackjack.main(Blackjack.java:72)

感谢您提前获得所有帮助!

Answer 1

很多问题......

• 你试图运行无法编译的代码 - 永远不要这样做.在尝试运行程序之前首先修复编译问题.
• 您正在尝试对尚未在类中声明的变量调用方法.如果您想要在其上调用方法,二十一点需要一个已初始化的牌组变量.
• 我会考虑创建一个包含ArrayList的Deck类,它具有一副牌的所有行为(方法).
• Card类不应该有deck字段.从逻辑上讲,为什么卡需要知道它所在的卡座.
• 卡绝对不应该扩展二十一点
• 相反,卡应该封装一张卡片的概念,意味着它的套装和等级,而不是别的.
• 稍后,如果需要,您可以使用HashMap将每个Card与Image或ImageIcon相关联.
• Card/Deck概念是教授enums时使用的规范示例之一,因此借用这个想法 - 将你的Suit和你的Rank放入枚举,并让你的Card类保持每个枚举的字段.

关于,

试图运行无法编译的代码是什么意思？

每当你看到这个:

Exception in thread "main" java.lang.Error: Unresolved compilation problem: 
    deck cannot be resolved

这恰恰意味着:您正在尝试运行无法编译的代码.您必须在编译阶段而不是在运行阶段修复此问题.

我的意思是,没有deck.shuffle(); ,它确实编译并运行正常.

然后,您必须deck.shuffle()在重新尝试运行代码之前修复错误.

是这种代码的结构方式,试图实现我的目标是不可能的？

我会从一开始就用干净的课程重新开始,特别是你的Card课程,这是一切的关键.使用我建议的枚举,在这里阅读它们:Java enums tutorial.

"二十一点需要一个甲板变量,如果你想在它上面调用一个方法,它就会被初始化."但是我想我可以在另一个类中使用Deck变量？

您只能在调用代码范围内的字段上调用方法.这是一个基本的Java 101概念,因此您最好查看如何在类上调用方法.你的Blackjack类没有deck字段,它在该类中根本不存在,因此你不能在不存在的字段或变量上调用方法.

我不能以某种方式从其他类引用数组,对象,变量,静态事物,任何你想要的等等吗？对不起,我缺乏理解,我仍然非常精简.

这些是超出本网站范围的基本问题,并建议您从重新审阅一本体面的Java书籍或教程的介绍性章节中受益.相信我,你不会后悔这样做.