如何从其他类修改arraylist？JAVA

我正在编写一个扑克游戏，并将所有卡存储在类组中创建的arraylist中：

public class Deck {

ArrayList<Card> deck = new ArrayList<Card>();

Deck(){  //Build the deck in order.

    for(int suit = 1; suit <= 4; suit++){
        for(int rank = 1; rank <= 13; rank++){
            Card card = new Card(rank, suit);
            deck.add(card);
        }
    }
}

公共类甲板{
ArrayList deck=新的ArrayList（）；
Deck（）{//按顺序构建Deck。
对于（int suit=1；suit每个
手牌
都有自己的
牌组
。您希望在多个手牌中共享一个
牌组

我想你想要这样的东西：

public class Hand {

    Deck deck;
    ArrayList<Card> myHand = new ArrayList<Card>();

    Hand(Deck deck) {
        this.deck = deck;
    }

    public void removeCard(Card card) {
        deckObject.deck.remove(card);
    }

    public void Draw() {
        for(int i = 0; i <= 4; i++) {
            myHand.add(deckObject.deck.get(0));
            deckObject.deck.remove(0);
        }
    }
}

供参考

Java惯例是使用小写方法（例如，
Draw
）
在构造函数中初始化变量通常更清晰
声明
List myHand
通常是首选，因为它具有更高的抽象级别
我会在你的
手上尝试这个
方法
Draw（）
，它应该真正命名为
Draw（）

一般来说，您不希望其他任何人干扰对象的内部状态。相反，您希望提供允许其他对象与其交互的方法，例如

public class Deck {

    private ArrayList<Card> deck = new ArrayList<Card>();

    Deck(){  //Build the deck in order.

        for(int suit = 1; suit <= 4; suit++){
            for(int rank = 1; rank <= 13; rank++){
                Card card = new Card(rank, suit);
                deck.add(card);
            }
        }
    }

    public Card[] draw(int count) {
        Card[] cards = new Card[count];
        if (count < deck.size()) {
            for(int i = 0; i < count; i++){
                cards[i] = deckObject.deck.remove(0);
            }        
        } else {
            throw new IllegalStateException("Can not with draw " + (count + 1) + " from deck that only has " + deck.size() + " cards");
        }
        return cards;
    }

公共类甲板{
private ArrayList deck=new ArrayList（）；
Deck（）{//按顺序构建Deck。
对于（int suit=1；suit，因为您正在创建一个Deck对象的新实例。您不想这样做。将Deck对象传递到Draw方法中，或生成一个单实例Deck对象。您不显示编排应用程序的主类，但应该在其中创建一个Deck对象，然后根据需要传递它。谢谢！这样做了。有道理，谢谢
Deck deck = new Deck();
Hand hand1 = new Hand(deck);
Hand hand2 = new Hand(deck);
hand1.Draw();
hand2.Draw();

    if (deckObject.deck.size() > 0) {        // Are there cards in the deck?
      myHand.add(deckObject.deck.remove(0)); // add the card removed from 
                                             // the deck to the Hand.
    } else {
      break;                                 // No cards.
    }
    // deckObject.deck.remove(0);            // Already taken care of.

public class Deck {

    private ArrayList<Card> deck = new ArrayList<Card>();

    Deck(){  //Build the deck in order.

        for(int suit = 1; suit <= 4; suit++){
            for(int rank = 1; rank <= 13; rank++){
                Card card = new Card(rank, suit);
                deck.add(card);
            }
        }
    }

    public Card[] draw(int count) {
        Card[] cards = new Card[count];
        if (count < deck.size()) {
            for(int i = 0; i < count; i++){
                cards[i] = deckObject.deck.remove(0);
            }        
        } else {
            throw new IllegalStateException("Can not with draw " + (count + 1) + " from deck that only has " + deck.size() + " cards");
        }
        return cards;
    }