使用 ArrayList 创建一副纸牌

Question

我知道以前很多人都问过这个问题（来这里之前我环顾了很多地方），但我似乎无法弄清楚如何修复我的代码。我的任务是制作一个静态 makeDeck 方法，该方法 returns 一个包含标准扑克牌的 52 张牌的 ArrayList。我是 ArrayLists 的新手，所以我不完全确定我是否正确初始化了我的 ArrayList makeDeck。这是我目前所拥有的：

    public class Card 
    { 
      private String mySuit; 
      private int myValue; 

      public Card( String suit, int value ) 
      { 
        mySuit = suit; 
        myValue = value; 
      } 

      public String name() 
      { 
        String[] cardNames =  
          { 
            "Deuce", "Three", "Four", "Five", 
            "Six", "Seven", "Eight", "Nine", "Ten", 
            "Jack", "Queen", "King", "Ace" 
          }; 

        return cardNames[ myValue - 2 ] + " of " + mySuit; 
      } 
    } 

    public class MainClass 
    { 
      public static void displayCards( ArrayList<Card> a ) 
      { 
        int i; 
        System.out.println( "Size is " + a.size() ); 
        for ( i = 0 ; i < a.size() ; i++ ) 
        { 
          Card c = a.get( i ); 
          System.out.println( "#" + (i+1) + ": " + c.name() ); 
        } 
      } 

    public static ArrayList<Card> makeDeck()
    {
      ArrayList<Card> cards = new ArrayList<Card>();
      String[] cardNames =  
          { 
            "Deuce", "Three", "Four", "Five", 
            "Six", "Seven", "Eight", "Nine", "Ten", 
            "Jack", "Queen", "King", "Ace" 
          }; 
      String[] suits = { "spades", "hearts", "diamonds", "clubs"  }; 

            for (int a=0; a<=cardNames.length(); a++)
            {
                for (int b=0; b<= suits.length(); b++)
                 {
                   cards.add(new Card(cardNames[a], suits[b]));  //I've noticed many people use this to add the card names and suits to the cards ArrayList, and it gives me an error of not being able to turn suits[b] into an integer, so I'm confused as to how it worked for others  

                 }
            }
return cards;
    }

    public static void main( String[] args )
    {
      System.out.println(makeDeck());
    }

如果有人能帮我弄清楚我做错了什么，我将不胜感激。谢谢！

Answer 1

您需要制作 makeDeck() return cards。同样在您的主要打印语句中，您遇到调用 makeDeck() 而不是 cards()

关于你的错误string cannot be converted to int你需要做以下两件事之一：

1) 更改 Card class 构造函数以接受两个字符串：

Public Card(string value, string suit)

并将int myValue更改为string myValue

2) 将您的 cardName 数组更改为 int 而不是 string。您也可以一起忽略 cardNames 并将插入更改为以下内容：

cards.add(new Card(suits[b], a+1));

Answer 2

添加 return 语句，该语句将 return 您的数组列表。

public static ArrayList<Card> makeDeck()
    {
      ArrayList<Card> cards = new ArrayList<Card>();
      String[] cardNames =  
          { 
            "Deuce", "Three", "Four", "Five", 
            "Six", "Seven", "Eight", "Nine", "Ten", 
            "Jack", "Queen", "King", "Ace" 
          }; 
      String[] suits = { "spades", "hearts", "diamonds", "clubs"  }; 

            for (int a=0; a<=12; a++)
            {
                for (int b=0; b<=3; b++)
                 {
                   cards.add(new Card(cardNames[a], suits[b]));  //I've noticed many people use this to add the card names and suits to the cards ArrayList, and it gives me an error of not being able to turn suits[b] into an integer, so I'm confused as to how it worked for others  

                 }
            }
    return cards;
    }

从您的主要方法调用 makeDeck()。

public static void main( String[] args ){
  ArrayList<Card> cards = makeDeck();

 for(Card c : cards){
   System.out.println("You can print card member variables here");
 } 

}

Answer 3

您正在将两个字符串传递给 Card 构造函数。在您编辑掉 Card class 的代码之前，我看到您的构造函数需要一个 String 和一个 int。这就是构造函数调用无法编译的原因。

此外，您忘记在 makeDeck() 方法中 return 一个值，并且您的 cards 列表是该方法的本地列表，因此您无法从main 方法，而且你没有 cards() 方法。

你的主要方法应该是：

public static void main( String[] args )
{
  System.out.println(makeDeck());
}

您的 makeDeck() 应该在最后一行有一个 return cards; 语句。

并且您应该更改 Card class 的构造函数或更改传递给它的 argumnets。

使用卡片的当前实现 class，您应该将卡片创建循环更改为：

    for (int a=0; a < suits.length; a++)
    {
        for (int b=0; b< 13 ; b++)
         {
           cards.add(new Card(suits[a],b));  
         }
    }

尽管如此，您可能必须更改 Card 的 name() 方法。

Answer 4

你似乎忘记了 return 在你的方法的最后，

public static ArrayList<Card> makeDeck()
{
  ArrayList<Card> cards = new ArrayList<Card>();
  String[] cardNames =  
      { 
        "Deuce", "Three", "Four", "Five", 
        "Six", "Seven", "Eight", "Nine", "Ten", 
        "Jack", "Queen", "King", "Ace" 
      }; 
  String[] suits = { "spades", "hearts", "diamonds", "clubs"  }; 

        for (int a=0; a<=12; a++)
        {
            for (int b=0; b<=3; b++)
             {
               cards.add(new Card(cardNames[a], b)); // <-- if the second Card 
               //                        parameter whould be an int.
             }
        }
    return cards;
}

你应该打电话给 makeDeck() 而不是 cards()

System.out.println(makeDeck());

使用 ArrayList 创建一副纸牌

Creating a Deck of Cards using an ArrayList

java

arraylist