不能在 main 中使用 ArrayList 方法

Question

我正在尝试为纸牌游戏编写模拟。我写了我的类和函数。我将尝试将我的卡片对象保存在 ArrayLists 中。但是主要我不能使用 ArrayList 的方法。我想我在 Representation 类中创建了 ArrayList 类型的 PileOfCards 对象。因为在 PileOfCards 类中，我在构造函数中创建了一个 ArrayList。所以我想让每次我们从 PileOfCards 类创建一个对象时，它的类型是 ArrayList。我的意思是我想在我的 PileOfCards 对象上使用 ArrayList 方法。但在我的主要内容中，我收到一个错误“对于 PileOfCards 类型的方法 size() 未定义”和 get(3)。我相信 PileOfCards 对象是 ArrayList 类型。为什么我有这样的错误。任何帮助将不胜感激。

// MY CARD CLASS
public class Card 
{

/* I assigned variables to numbers because I can use them later easily.
 * And they can not be changed
 */
public final static int red     = 0;
public final static int black    = 1;

public final static int heart = 0;
public final static int spade = 1;
public final static int diamond = 2;
public final static int club = 3;

public final static int ace     = 0;
public final static int jack    = 10;
public final static int queen    = 11;
public final static int king    = 12;

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

private int value;
private int suit;
boolean faceUp;

// Create card object with parameters.
Card(int value_in, int suit_in, boolean face_type)
{

    value = value_in;
    suit = suit_in;
    faceUp = face_type;
}

// Make the card face up
public void faceUp()
{
    faceUp = true;
}

// Make the card face down
public void faceDown()
{
    faceUp = false;
}

// return card is face up or face down
public final boolean cardStatus()
{
    return faceUp;
}

// return the value of the card
public final int cardValue()
{
    return value;
}

// return the suit of the card
public final int cardSuit()
{
    return suit;
}

// return the color of the card
public final int color()
{
    if(cardSuit()==heart || cardSuit()==diamond)
    {
        return red;
    }
    else
    {
        return black;
    }
}

public String toString() {
    return ("Card Suit: "+this.cardSuit()+
            " Card Value: "+ this.cardValue() +
            " Card Status: "+ this.cardStatus() +
            " Color : " + this.color());
   }
}
//--------------------------------------------------------------------------------

// MY PILEOFCARDS CLASS
import java.util.*;

public class PileOfCards 
{
/* I created pile as ArrayList because the elements of the list will change.
 * So using ArrayList is more useful and easier.
 */
public ArrayList<Card> pile;

//create an empty pile
PileOfCards()
{

    // Create pile with card objects
    this.pile = new ArrayList<Card>();
}

//create a deck with 52 cards
public void makeDeck()
{

    for (int a=0; a<=3; a++)
    {
        for (int b=0; b<=12; b++)
        {
            pile.add(new Card(a, b, false)); 
        }
    }

}

// shuffling the cards
public void shuffle()
{

    Collections.shuffle(this.pile);
}

// get the top card and remove that. I think the first element of the list as top card
public Card takeTopCard()
{

    if(pile.isEmpty()) 
    {
        return null; 
    }
    else 
    {    
        Card top = pile.get(0);
        pile.remove(0);
        return top;
    }
}

// add a specific card to the pile
public void addCardToPile(Card c)
{

    pile.add(c);
}

// determines the pile can take card
public boolean canTakeSuit (Card aCard)  
{   if (pile.isEmpty())
        return aCard.cardValue() == 0;
    Card topCard = pile.get(0);
    return (aCard.cardSuit() == topCard.cardSuit()) &&
        (aCard.cardValue() == 1 + topCard.cardValue());
}


public boolean canTakeValue (Card aCard) 
{   if (pile.isEmpty())
        return aCard.cardValue() == 12;
    Card topCard = pile.get(0);
    return (aCard.color() != topCard.color()) &&
           (aCard.cardValue() == topCard.cardValue() - 1);
}

public void selectSuit () 
{   if (pile.isEmpty())
        return;

    // if face down flip the card
    Card topCard = pile.get(0);
    if ( topCard.cardStatus() != true) 
    {   
        topCard.faceUp();
    }

    pile.remove(0);

    if(canTakeSuit(topCard))
    {
        pile.add(topCard);
    }
    else
    {
    addCardToPile(topCard);
    }
}

public void selectValue () 
{   if (pile.isEmpty())
        return;

    // if face down flip the card
    Card topCard = pile.get(0);
    if ( topCard.cardStatus() != true) 
    {   
        topCard.faceUp();
    }

    pile.remove(0);

    if(canTakeValue(topCard))
    {
        pile.add(topCard);
    }
    else
    {
    addCardToPile(topCard);
    }
}
}
    //--------------------------------------------------------------------------
// MY REPRESENTATION CLASS
public class Representation
{

// create the main pile. we will deal the cards from here
static PileOfCards mainPile = new PileOfCards();

// create a pile for opening cards. This pile can hold only one card.
static PileOfCards oneCardPile = new PileOfCards();

// create a pile that holds the cards in one suit from ace to king
static PileOfCards oneSuitPile1 = new PileOfCards();

// create a pile that holds the cards in one suit from ace to king
static PileOfCards oneSuitPile2 = new PileOfCards();

// create a pile that holds the cards in one suit from ace to king
static PileOfCards oneSuitPile3 = new PileOfCards();

// create a pile that holds the cards in one suit from ace to king
static PileOfCards oneSuitPile4 = new PileOfCards();

// create the pile that holds one card at the beginning - max. 13 cards
static PileOfCards firstPile = new PileOfCards();

// create the pile that holds 2 cards at the beginning - max. 13 cards
static PileOfCards secondPile = new PileOfCards();

// create the pile that holds 3 cards at the beginning - max. 13 cards
static PileOfCards thirdPile = new PileOfCards();

// create the pile that holds 4 cards at the beginning - max. 13 cards
static PileOfCards fourthPile = new PileOfCards();

// create the pile that holds 5 cards at the beginning - max. 13 cards
static PileOfCards fifthPile = new PileOfCards();

// create the pile that holds 6 cards at the beginning - max. 13 cards
static PileOfCards sixthPile = new PileOfCards();

// create the pile that holds 7 cards at the beginning - max. 13 cards
static PileOfCards seventhPile = new PileOfCards();
}
//-------------------------------------------------------------------------
// MY DEMO CLASS
import java.util.*;

public class Demo
{

public static void main(String[] args)
{

    Representation.mainPile.makeDeck();
    for(int i=0; i<Representation.mainPile.size(); i++)
    System.out.println(Representation.mainPile.get(i));
}

}

Answer 1

只需在 PileOfCards 类中添加一个方法大小，它将返回 arrayList 的大小：

public int size(){
   return pile.size();
} 

并获得卡片：

public Card get(int index){
   return pile.get(index);
}

我不是将 PileOfCards 对象创建为数组列表吗？

不，你没有，PileOfCards 是一个类，它可以构造 PileOfCards 类型的对象，这些对象的属性是 arrayList。

Answer 2

您的PileOfCards 类本身不是ArrayList，它只有该类型的属性。

使用Representation.mainPile.pile.size() 而不仅仅是Representation.mainPile.size()。