数组是空的吗？

Question

所以我试图找出代码中 ArrayOutOfBoundException 错误的可能来源。

代码的目的是将一堆卡片打印到记事本文件中，如下所示：

public void printCardPiles (PrintWriter writer)
{
  writer.println("Piles: ");

  for (int i = 0; i < piles.size(); i++)      

    {

       writer.println();
       MyArrayList<Card> tester = piles.get(i).getList();    

       writer.print(tester.toString());


    }

}

问题是我不断收到 ArrayIndexOutOfBoundsException，但我不太清楚源是从哪里来的。

我注意到即使我将代码更改为：

public void printCardPiles (PrintWriter writer)
{
  writer.println("Piles: ");

  for (int i = 0; i < 1; i++) // CHANGE: i < piles.size() to i < 1
    {

       writer.println();
       MyArrayList<Card> tester = piles.get(i).getList();


       writer.print(tester.toString());


    }

}

无论如何，我仍然遇到越界异常。

异常指向行 writer.print(tester.toString()); 那么这可能是来源吗？确切的例外情况如下（为上下文添加了注释）：

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: -1
at Card.toString(Card.java:134)                          // Sets up a card object      
at java.lang.String.valueOf(String.java:2994)
at java.lang.StringBuilder.append(StringBuilder.java:131)
at MyArrayList.toString(MyArrayList.java:168)
at Table.printCardPiles(Table.java:199)                  // The exception location
at SortCardGame.playGame(SortCardGame.java:113)          // Where the exception's method is being called from 
at SortCardGame.main(SortCardGame.java:52)

这是否意味着代码正在使用一个空数组（在这种情况下，空数组将是一堆）。是什么导致了异常？或者是别的什么？

注意：卡片的 toString() 也如下所示：

public String toString()
{
    String printString = RANKS[rank - 1] + SUITS[suit - 1];    // RANKS is the the array holding all the possible Ranks 
                                                               // rank is what rank the current card is
                                                               // Same as the above
    return printString;
}

感谢大家的帮助，我知道这很模糊，但我可以根据需要提供更多详细信息。我主要是在寻找一些关于从哪里开始寻找问题的想法，或者可能导致问题的原因。

编辑： 根据要求，我添加了整个卡片 Class。

public class Card implements Comparable<Card>
{
// For printing the card rank

public static String[] RANKS =
{
    " A", " 2", " 3", " 4", " 5", " 6", " 7", " 8", " 9", "10", " J", " Q", " K"
};

// For printing the card suit

public static String[] SUITS =
{
    "-C", "-D", "-H", "-S"
};

// private instance variables

private int rank;
private int suit;

// Default Constructor: initialize to Ace of Clubs

public Card()
{
    rank = 1;
    suit = 1;
}

// Two-Param Constructor : initialize rank and suit

public Card (int initRank, int initSuit)
{
    rank = initRank;
    suit = initSuit;
}

// Copy constructor: Copies a Card from another Card

public Card (Card otherCard)
{
    otherCard.rank = rank;
    otherCard.suit = suit;
}

// Returns relative position of this Card to someCard.
// This compares the Cards, first by rank: Aces low, King High
// then Suit within rank: CLUB=1, DIAMOND=2, HEART=3, SPADE=4

public int compareTo (Card someCard)
{
    if (rank > someCard.rank)
    {
        if (suit > someCard.rank)
        {
            return 1;
        }
        else if (suit < someCard.rank)
        {
            return -1;
        }
        else
        {
            return 0;
        }
    }
    else if (rank < someCard.rank)
    {
        if (suit > someCard.rank)
        {
            return 1;
        }
        else if (suit < someCard.rank)
        {
            return -1;
        }
        else
        {
            return 0;
        }
    }
    else
    {
        if (suit > someCard.rank)
        {
            return 1;
        }
        else if (suit < someCard.rank)
        {
            return -1;
        }
        else
        {
            return 0;
        }
    }



}



// Determines whether this Card has the same rank and suit
// as another Card passed in - Note cast of obj to Card

@Override
public boolean equals (Object obj)
{
    Card someCard = (Card) obj;
    return (someCard.compareTo (this) == 0);
}

// Print the card's rank and suit using the static
// String arrays defined about

public String toString()
{
    String printString = RANKS[rank - 1] + SUITS[suit - 1];
    return printString;
}

}

快速说明，我没有写卡片的 equals() 或 toString() Class。

Answer 1

我猜你是使用拷贝构造函数的问题。该问题使实例的 rank 和 suit 为 0。这使得 toString 无法正常工作

public Card (Card otherCard)
{
    otherCard.rank = rank;
    otherCard.suit = suit;
}

这应该是

public Card (Card otherCard)
{
    this.rank = otherCard.rank;
    this.suit = otherCard.suit;
}

Answer 2

我认为异常是因为这条线

String printString = RANKS[rank - 1] + SUITS[suit - 1];

请确保rank-1和suit-1的值大于等于0。等级>=1 且花色>=1

数组是空的吗？

Is the array empty?

java

arrays

exception

arraylist

tostring