从数组创建 toString

Question

我正在尝试创建一个 toString 来打印我的数组的详细信息。我可以通过执行 for 循环并在 toString 中使用 print 行来打印我希望它的外观，但是当我想在代码的主要部分中使用它时，显然它并没有真正起作用。

对于上下文，这就是我对 Card 的看法：

/** 
 * Constructor for the card. If damageDone and mana are negative they are replaced by 1 
 * (not the best solution but the good enough until we cover exception handling later in the 
 * semester). <br>
 * My solution length: 8 lines
 * @param manaCost - The amount of mana this spell costs to cast
 * @param damageDone - The amount of damage done by this card
 * @param name  - the name of this card
 */

public Card(int manaCost, int damageDone, java.lang.String name) {
    if (damageDone < 0) {
        this.damageDone = 1;}
    else {this.damageDone = damageDone;}
    if (manaCost < 0) {
        this.manaCost = 1;}
    else {this.manaCost = manaCost;}
    this.name = name;}

这是我的示例，这段代码适用于我希望它的外观，但实际上没有返回任何结果：

public java.lang.String toString(){
    int count = 0;
    for (int index = 0; index < card.length; index++) {
        count++; 
        System.out.println(count + ": " + card[index]); 
    }
    return "";}

所以我尝试构建一个字符串方法，但它没有返回任何结果，我很困惑。有没有人知道我哪里出错了。

@Override
public java.lang.String toString(){
    String output = "";
    for (int index = 0; index < card.length; index++) {
        output = output + card[index];
    }
    return output;}

我正在学习的完整课程如下 我在正在解决的其他领域仍然存在问题：

public class Deck {

    private Card[] card = new Card[100];

private int cardsRunning = 100;
static int DECKSIZE = 100;
static java.lang.String emailID = "MITNY013";
private boolean random = true;



/**
 * Constructor for the Deck. Adds the following cards to the deck in the following order
 * 4x Super Lucky Strike, Damage 100, Mana 2 
 * 6x Mega Santa Hit, Damage 80, Mana 2
 * 10x Critical Hit, Damage 50, Mana 5
 * 10x Massive Strike, Damage 40, Mana 7
 * 15x Wrong Way Down A One Way Street, Damage 30, Mana 10
 * 15x Bender Rules Here, Damage 15, Mana 10
 * 40x Trade, Damage 5, Mana 5 <br>
 * My solution length: 16 lines (space lines not included)
 * @param random - Whether to turn on random features
 */

public Deck(boolean random) {
    for (int index = 0; index <= 3; index++) {
        card[index] = new Card( 2, 100, "Lucky Strike");
    }
    for (int index = 4; index <= 10; index++) {
        card[index] = new Card( 2, 80, "Santa Hit");
    }
    for (int index = 11; index <= 20; index++) {
        card[index] = new Card( 5, 50, "Critical Hit");
    }
    for (int index = 21; index <= 30; index++) {
        card[index] = new Card ( 7, 40, "Massive Strike");
    }
    for (int index = 31; index <= 45; index++) {
        card[index] = new Card( 10, 30, "Wrong Way Down A One Way Street");
    }
    for (int index = 46; index <= 60; index++) {
        card[index] = new Card( 10, 15, "Bender Rules Here");
    } 
    for (int index = 61; index <= 99; index++) {
        card[index] = new Card( 5, 5, "Trade");
    } 
}

/**
 * Returns a string representation of the entire deck in the format
 * Deck [ 1:Card [name=Super Lucky Strike, manaCost=2, damageDone=100]
 *        2:Card [name=Super Lucky Strike, manaCost=2, damageDone=100]
 *        3:Card [name=Super Lucky Strike, manaCost=2, damageDone=100]
 *        4:Card [name=Super Lucky Strike, manaCost=2, damageDone=100]] <br>
 * My solution length: 7 lines
 * @overrides - toString in class java.lang.Object
 */

@Override
public java.lang.String toString(){
    String output = "";
    for (int index = 0; index < card.length; index++) {
        output = output + card[index];
    }
    return output;}



/**
 * Uses a random number generator to get a card from the deck somewhere then swaps the 
 * last card in the deck to that position and reduces the cardsRemaining by one. 
 * This is important. if the random flag is false you should always get the card at 
 * position 0. When you swap the card out you should also set the old position to null 
 * for safety. <br>
 * My solution length: 10 lines
 * @return - the card drawn or null if no cards left in deck
 */

public Card getRandomCard() {
    // use random number generator
    Random rand = new Random();
    int randomCardNo = rand.nextInt(getCardsRemaining());
    removeCard(randomCardNo);
    return card[randomCardNo];
}

/**
 * Return the number of cards remaining in the deck.
 * My solution length: 6 lines
 * @return - the total cards remaining
 */

public int getCardsRemaining() {
    int temp = 100;
    for (int index = 0; index < card.length; index++) {
        if ((card[index] == null) ) {
            temp = temp -1;
        }}
    cardsRunning = temp;
    return cardsRunning;}

/**
 * BONUS Method
 * My solution length: XXX
 * @return - shuffle cards in deck 
 */

public void shuffle(Card[] card) {
    int index; 
    Card temp;
    Random random = new Random();
    for (int i = card.length - 1; i > 0; i--){ 
        index = random.nextInt(i + 1);
        temp = card[index];
        card[index] = card[i];
        card[i] = temp;}}

private void removeCard(int no) {
    int size = card.length;
    Card[] newCard = new Card[size];
    int index = 0;
    for (int i = 0; i < size; i++) {
        if (card[i] != null) {
            newCard[index++] = card[i];
        }
    }
    }
}

Answer 1

您需要在Card 和Deck 两个类中重写toString 方法，如下所示：

public class Card {
    int manaCost;
    int damageDone;
    String name;

    public Card(int manaCost, int damageDone, String name) {
        if (damageDone < 0) {
            this.damageDone = 1;
        } else {
            this.damageDone = damageDone;
        }
        if (manaCost < 0) {
            this.manaCost = 1;
        } else {
            this.manaCost = manaCost;
        }
        this.name = name;
    }

    // ...

    @Override
    public String toString() {
        return "Card [manaCost=" + manaCost + ", damageDone=" + damageDone + ", name=" + name + "]";
    }
}

public class Deck {
    private Card[] cards;

    public void setCards(Card[] cards) {
        this.cards = cards;
    }

    // ...

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < cards.length; i++) {
            sb.append(cards[i].toString() + "\n");
        }
        return sb.toString();
    }
}

测试：

public class Main {
    public static void main(String[] args) {
        Card[] cards= {
                new Card( 2, 100, "Lucky Strike"),
                new Card( 2, 80, "Santa Hit"),
                new Card( 5, 50, "Critical Hit")
        };
        Deck deck1 = new Deck();
        deck1.setCards(cards);
        System.out.println(deck1);
    }
}

输出：

Card [manaCost=2, damageDone=100, name=Lucky Strike]
Card [manaCost=2, damageDone=80, name=Santa Hit]
Card [manaCost=5, damageDone=50, name=Critical Hit]

Answer 2

很高兴知道卡片是什么。话虽如此，一个非常简单的方法是使用 Arrays#toString。

public java.lang.String toString(){
    return Arrays.toString(card);
}