在 while 循环中防止 IndexOutOfBoundsException [Java]

Question

我正在制作一个纸牌游戏，它运行良好，但我无法在不遇到 IndexOutOfBoundsException 错误的情况下到达牌组底部。我有一个 1 到 52 之间的随机数字数组，我用它来选择从我拥有的卡片数组列表中调用的索引。由于卡片组是一个 ArrayList，我可以在每次循环后轻松移除每张卡片。但是我无法从随机数数组中删除数字，因此随着卡片列表变小，调用索引过高的机会就越大。想不出办法。我尝试使用 if 语句将随机数的值更改为小于 arrayList 的最大长度的值，但仍然出现错误。

public static void main(String[] args) {
    // TODO Auto-generated method stub
    System.out.println("Welcome to War! Press enter to begin."); //User prompt
    Scanner scanner = new Scanner(System.in); //Scanner init
    String[] suit = {" of Diamonds", " of Spades", " of Hearts", " of Clubs"};//Array for suits
    String[] faces = {"Ace", "2", "3", "4", "5", "6", "7", "8", "9", "10", "Jack", "Queen", "King"};//Array for faces
    String[] deck = new String[52]; //Deck size setup
    boolean deckComplete = false;//Boolean for deck being finished
    int[] random = new int[52];//Array for all numbers between 0 and the number of cards in the deck multiplied by number of decks
    ArrayList<Integer> random1 = new ArrayList<Integer>();
    int playerOneTotal = 0;
    int playerTwoTotal = 0;



    for (int x = 0; x<random.length; x++) {
        random[x] = x;
    }//Content setup for random array

    Random rndNum = new Random();//Random init

    int i = 0;

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

            deck[i] = faces[i % 13] + suit[i % 4];
        }//Deck of cards setup



    ArrayList<String> arrayList = new ArrayList<String>(Arrays.asList(deck));//Changing Array with card contents into an ArrayList

    while (deckComplete == false) {         //While loop for dealing cards


        for (int j = deck.length; j >= 1; j--) {


           // System.out.println("Hit enter to be dealt a card!");    
            String readString = scanner.nextLine(); //Set variable "readString" to user input
            int randomNumber = rndNum.nextInt(j);
            int randomNumberTwo = rndNum.nextInt(j);


            if (readString.equals("")) {        //If user input equals "enter"...

                 if (randomNumber >= arrayList.size()) {
                    randomNumber = arrayList.size() - 1;
                }

                if (randomNumberTwo == arrayList.size()) {
                    randomNumberTwo = arrayList.size() - 1;
                }


                  int playerOne = random[randomNumber];
                  int playerTwo = random[randomNumberTwo];
                  int playerOneScore = 0;
                  int playerTwoScore = 0;


                  System.out.println("Player One Draws a: " + arrayList.get(random[randomNumber])); //Print out card
                  arrayList.remove(random[randomNumber]); //Remove card from deck
                  System.out.println("Player Two Draws a: " + arrayList.get(random[randomNumberTwo])); //Print out card
                  arrayList.remove(random[randomNumberTwo]); //Remove card from deck


                  playerOneTotal = playerOneTotal + playerOneScore;
                  playerTwoTotal = playerTwoTotal + playerTwoScore;

                  if (playerOneTotal > playerTwoTotal) {
                      System.out.println("Player One Wins this round! Current Score - Player One: " + playerOneTotal + " Player Two: " + playerTwoTotal);
                  }else if (playerOneTotal < playerTwoTotal) {
                      System.out.println("Player Two Wins this round! Current Score - Player One: " + playerOneTotal + " Player Two: " + playerTwoTotal);
                  }else if (playerOneTotal == playerTwoTotal) {

                  }


                   if (j == 1) {    //If program gets to last card...
                       deckComplete = true; //Set desk complete to true

                       System.out.println(arrayList.get(random[randomNumber])); //Print last card
                       arrayList.remove(random[randomNumber]); //Remove last card
                       System.out.println("You are out of cards!"); //Print "You are out of cards"
                       break; //Stop loop
                   }  
               }



       }

除了尝试（如下）之外，还有什么方法可以让我得到正确的结果吗？

if (randomNumber >= arrayList.size()) {
                    randomNumber = arrayList.size() - 1;
                }

                if (randomNumberTwo == arrayList.size()) {
                    randomNumberTwo = arrayList.size() - 1;
                }

编辑：这是确切的错误消息。

Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 33, Size: 23 at java.util.ArrayList.rangeCheck(ArrayList.java:635) at java.util.ArrayList.get(ArrayList.java:411) at Game.main(Game.java:72)

Answer 1

如果我没看错，你每回合都会从ArrayList 中随机选择一张牌。通过在游戏开始时将整个ArrayList 洗牌（类似于在现实生活中洗牌的方式），您可以使您的生活变得更轻松。然后您可以简单地删除列表的第一个（或最后一个）元素，而不必担心IndexOutOfBoundsException。

要洗牌整副牌，请使用Collections.shuffle：

Collections.shuffle(fileList, new Random());

从牌库中取出最上面的牌：

arrayList.remove(0);

Answer 2

您拥有deck，这是按顺序排列的 52 张卡片的完整列表。

您创建arrayList 作为它的副本，就像您所做的那样，只是将其重命名为stack（或cardStack），然后：

• 使用Collections.shuffle() 随机播放stack
• 使用remove(stack.size()-1)（或remove(0)，但速度较慢）从stack 获取卡片。

更好的是，使用 ArrayDeque 而不是 ArrayList，因为它可以用作 LIFO（后进先出）堆栈。在您的情况下，您将使用stack.pop() 拿一张卡片。

---

跟进

为了让游戏正常运行，一张牌必须不仅仅是文字“黑桃 A”。你需要知道它是一个 A，它是一个 Spade，所以你需要一个类，例如命名为 Card，有两个字段：suit 和 face。然后该类的toString() 方法将返回“黑桃A”。

还请注意，除非您想作弊，否则您永远不会使用索引访问 cardStack。洗牌后唯一允许的操作是pop()，取走栈顶的牌。

您的整个循环将如下所示：

// Build deck
...

// Create shuffled stack
Deque<Card> cardStack = new ArrayDeque<>(Arrays.asList(deck));
Collections.shuffle(cardStack, rndNum);

// Play game
while (! cardStack.isEmpty()) {
    Card player1card = cardStack.pop();
    Card player2card = cardStack.pop();

    // do you stuff here
}