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（在来这里之前我环顾了一下），但我似乎无法弄清楚如何修复我的代码。 我的任务是创建一个静态的makeDeck方法，该方法返回一个ArrayList，其中包含一副标准纸牌的52张牌。 我对ArrayLists相当陌生，所以我不完全确定我是否正确初始化了我的ArrayList makeDeck。 这是我到目前为止所拥有的：

    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

你正在将两个字符串传递给你的Card构造函数。在您编辑 Card 类的代码之前，我看到您的构造函数需要一个字符串和一个 int。这就是构造函数调用不编译的原因。

此外，您忘记在 makeDeck() 方法中返回一个值，并且您的cards列表是该方法的本地列表，因此您无法从 main 方法访问它，并且您没有 cards() 方法。

您的主要方法应该是：

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

您的makeDeck()的最后一行应有一个return cards;语句。

你应该要么改变你的Card类的构造函数，要么改变你传递给它的argumnets。

使用卡类的当前实现，您可能应该将卡创建循环更改为：

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

不过，您可能需要更改name() Card方法。

Answer 2

您需要

返回makeDeck() cards。 同样在您的主要印刷声明中，您见面是打电话给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） 将 Card 类构造函数更改为包含两个字符串：

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并将插入的内容更改为以下内容：

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

Answer 3

似乎你忘了在方法结束时return，

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());

Answer 4

添加return将返回数组列表的语句。

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;
    }

从主方法调用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");
 } 
}