使用ArrayList创建卡片组

Question

我知道以前很多人都问过这个问题（在来到这里之前我环顾了一下），但是我似乎无法弄清楚如何解决我的代码。 我的任务是制作一个静态makeDeck方法，该方法返回一个ArrayList，其中包含标准纸牌中的52张纸牌。 我是ArrayList的新手，所以我不确定我是否正确初始化了ArrayList的makeDeck。 这是我到目前为止的内容：

    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());
    }

如果有人可以帮助我弄清楚我在做什么错，我将不胜感激。 谢谢！

Answer 1

您正在将两个String传递给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String和一个int。 这就是构造函数调用无法编译的原因。

另外，您忘了在makeDeck()方法中返回值，并且您的cards列表在该方法的本地，因此您无法从主方法访问它，而且您也没有cards()方法。

您的主要方法应为：

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

您的makeDeck()应该有一个return cards; 最后一行中的语句。

您应该更改Card类的构造函数或更改传递给它的argumnet。

使用Card类的当前实现，您可能应该将Card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，您可能必须更改Card的name()方法。

Answer 2

您需要使makeDeck()返回cards 。 同样在您的主打印语句中，您遇到要调用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）更改Card类构造函数以采用两个字符串：

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 。 您也可以全部忽略cardNames ，然后将其更改为以下内容：

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

Answer 3

添加return语句，该语句将返回您的数组列表。

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 4

看来您忘了在方法结束时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;
}

而且您应该调用makeDeck()而不是cards()

System.out.println(makeDeck());