java - 如何在不创建数组的情况下检查重复值？

Question

我有一个程序，可以根据随机数的值发 20 张牌。到目前为止，它可以处理黑桃 K、红心 2 等牌。我的工作是使用方法检查牌是否重复，但没有数组。这是我检查重复项的解决方案，但由于明显的原因而不起作用:

    public class Driver {
        public static void main(String [] args) {

            for (int i = 0; i < 20; i++){
                Cards card1 = new Cards();
                Cards card2 = card1;
                if (card1 == card2) {
                    card1 = new Cards(); 
                }
                System.out.println(card1);
            }
        }
    }

这是我的支持类(class):

import java.util.Random;

public class Cards {

    String hearts = "Hearts";
    String diamonds = "Diamonds";
    String clubs = "Clubs";
    String spades = "Spades";

    String suit; 
    int cardNumber; 
    String numberName; 
    String suitName;
    Random randomNum = new Random();

    public Cards () {

    }

    public String suit() {
        int theRandom = randomNum.nextInt(4);

        if (theRandom == 0 ) {           
            suitName = "hearts";
        }
        else if ( theRandom == 1) {
            suitName = "diamonds"; 
        }
        else if (theRandom == 2) {
            suitName = "clubs";
        }
        else {
            suitName = "spades";
        }
        return suitName;
    }
    public String number() {
        int theRandomNum = randomNum.nextInt(12 + 1); 

        if ( theRandomNum == 1 ) {

            numberName = "Ace";
        }
        else if ( theRandomNum == 2) {
            numberName = "2";
        }
        else if ( theRandomNum == 3) {
            numberName = "3";
        }
        else if ( theRandomNum == 4) {
            numberName = "4";
        }
        else if ( theRandomNum == 5) {
            numberName = "5";
        }
        else if ( theRandomNum == 6) {
            numberName = "6";
        }
        else if ( theRandomNum == 7) {
            numberName = "7";
        }
        else if ( theRandomNum == 8) {
            numberName = "8";
        }
        else if ( theRandomNum == 9) {
            numberName = "9";
        }
        else if ( theRandomNum == 10) {
            numberName = "10";
        }
        else if ( theRandomNum == 11) {
            numberName = "Jack";
        }
        else if ( theRandomNum == 12) {
            numberName = "Queen";
        }
        else if ( theRandomNum == 13) {
            numberName = "King";
        } 
        return numberName;
    }

    public String toString()
    {
        if (number() == "null") {
            return ("3" + " of " + suit());
        }

        return (number() + " of " + suit());
    }
}

Answer 1

使用大字符串来存储已选择的卡片:

String cards = "";

for(int i = 0; i < 20; i++)
{
    Cards card = new Cards();
    while(cards.contains(card.toString()))
        card = new Cards(); //keep generating a random card until it's a new card
    cards += card.toString(); //add the card to the string of cards
    System.out.println(card);
}

此代码将进入您的 Driver 类的 main 方法