Question

我知道很多人之前已经问过这个问题（我来之前看了很多），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makeDeck方法，该方法返回一个包含标准牌组的52张牌的ArrayList。我对ArrayLists相当新，所以我不能完全确定我是否正确初始化了我的ArrayList makeDeck。这就是我到目前为止所做的：

    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());
    }

如果有人能帮助我弄清楚我做错了什么，我将非常感激。谢谢！

Answer 1

您正在将两个字符串传递给Card构造函数。在编辑Card类的代码之前，我看到你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()方法中返回值，并且您的cards列表是该方法的本地列表，因此您无法通过主方法访问该列表，并且你还没有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()最后一行应该有一个return cards;声明。

您应该更改Card类的构造函数或更改传递给它的argumnets。

使用Card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));  
         }
    }

您可能不得不更改name()的{{1}}方法。

Answer 2

您需要makeDeck()返回cards。您也可以在主要打印声明中致电makeDeck()而不是cards()

关于您的错误string cannot be converted to int，您需要执行以下两项操作之一：

1）将Card类构造函数更改为两个字符串：

Public Card(string value, string suit)

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并更改您插入以下内容：

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

Answer 3

添加将返回数组列表的return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;
    }

从您的主要方法中致电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 4

您的方法结束时似乎忘了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;
}

您应该致电makeDeck()而不是cards()

System.out.println(makeDeck());

使用ArrayList创建卡片组

4 个答案: