13、Java——“21点”扑克游戏系统（变量+循环）

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                   Java——对象和类案例代码详解

⛳️ 一、项目需求

** 编写“21点”的扑克游戏（每个需求用一个测试类来完成测试）**

**需求一： 计算机随机地向用户发5张牌，如果牌的总点数小於或等於21点，则用户赢；超过21点则计算机赢。**

    注意类的没有参数的构造器随机产生一张牌，并且不会重复发牌。类模仿真实牌局的行为，可以用getValue方法从一副牌中重复抽取牌。

    你的程序应该：

    抽取一张牌；

    向用户显示这张牌；

    显示到目前为止已发牌的总点数

** 需求二： 为使程序更象真实的牌局，用户应该能与计算机互动玩牌。修改刚才的程序，计算机仍然抽取5张牌，不超过21点的是赢家，如果双方都不超过21点，则双方都不算赢，你的程序应该能准确地报告结果。**

    程序应该：

    为用户和计算机抽牌；

    向用户显示牌；

    分别显示用户和计算机的当前总点数；

    为使游戏更加有趣，每抽一张新牌时都要显示牌和总点数

** 需求三： 修改程序使用户可以选择是否抽牌，而规定计算机必须抽5张牌或直到牌的总点数大於等於21**

**需求四： 修改程序使得用户可以一直玩下去，并分别累计用户和计算机赢的牌局数。**

⛳️ 二、代码实现

1、提供默认引用类Card类，代码如下：

package cn.bdqn.demo04 ;

/**
 * Represents a playing card
 * @author Roger Garside/John Mariani
 * @version Last Rewritten: 16th Sept 1997
 */

import java.util.* ;

public class Card
    {
    // Card Class Variables

    private static boolean initialised = false ;
    private static Random rand = new Random() ;
    private static boolean[][] dealt = new boolean[4][13] ;
    private static int noDealt ;

    // Card Instance Variables

    /*
     * the suit of the card (0 to 3)
     */
    private int suit ;
    /*
     * the value of the card (0 to 12)
     */
    private int value ;

    // Card Class Constants

    /**
    * Constant - Spades
    */
    public static final int SPADES = 0 ;
    /**
    * Constant - Hearts
    */
    public static final int HEARTS = 1 ;
    /**
    * Constant - Clubs
    */
    public static final int CLUBS = 2 ;
    /**
    * Constant - Diamonds
    */
    public static final int DIAMONDS = 3 ;

    // Card Constructor Methods

    /**
     * Creates an instance of the Card class with random values
     * (if all have been dealt, then starts again)
     */
    public Card()
    {
        if (noDealt == 52)
            {
        System.err.println("all 52 cards dealt") ;
            initialised = false ;
            }
    if (!initialised)
        {
        for (int i = 0 ; i < 4 ; i++)
            for (int j = 0 ; j < 13 ; j++)
            dealt[i][j] = false ;
        initialised = true ;
        noDealt = 0 ;
        }
    int s, v ;
    do
        {
        s = (int) (Math.abs(rand.nextInt()) % 4) ;
        v = (int) (Math.abs(rand.nextInt()) % 13) ;
        }
        while (dealt[s][v]) ;
    dealt[s][v]  = true ;
        suit = s ;
    value = v ;
        noDealt++ ;
    } // end of constructor method

    /**
     * Creates an instance of the Card class with specified values
     * (if all have been dealt, then starts again)
     * @param s suit of the card
     * @param v value of the card
     */
    public Card(int s, int v)
    {
        if (noDealt == 52)
            {
        System.err.println("all 52 cards dealt") ;
            initialised = false ;
            }
    if (!initialised)
        {
        for (int i = 0 ; i < 4 ; i++)
            for (int j = 0 ; j < 13 ; j++)
            dealt[i][j] = false ;
        initialised = true ;
        noDealt = 0 ;
        }
        if ((s < 0) || (s > 3))
            {
            System.out.println("invalid suit") ;
            System.exit(1) ;
            }
        if ((v < 0) || (v > 12))
            {
            System.out.println("invalid value") ;
            System.exit(1) ;
            }
        if (dealt[s][v]) ;
            {
            System.out.println("card already used") ;
            System.exit(1) ;
            }
    dealt[s][v]  = true ;
        suit = s ;
    value = v ;
        noDealt++ ;
    } // end of constructor method

    // Card Instance Methods - Selectors

    /**
     * returns the suit attribute of the card
     * @return the suit attribute of the card
     */
    public int getSuit()
    {
    return suit ;
    } // end of method getSuit

    /**
     * returns the suit attribute of the card as a string
     * @return the suit attribute of the card as a string
     */
    public String getSuitString()
    {
    switch (suit)
        {
        case SPADES :
        return "Spades" ;
        case HEARTS :
        return "Hearts" ;
        case CLUBS :
        return "Clubs" ;
        case DIAMONDS :
        return "Diamonds" ;
            default :
        return "Unknown" ;
            }
    } //end of method getSuitString

    /**
     * returns the value attribute of the card
     * @return the value attribute of the card
     */
    public int getValue()
    {
    return value ;
    } // end of class getValue

    /**
     * returns the value attribute of the card as a string
     * @return the value attribute of the card as a string
     */
    public String getValueString()
    {
    switch (value)
        {
        case 0 :
        return "Ace" ;
        case 1 :
        return "two" ;
        case 2 :
        return "three" ;
        case 3 :
        return "four" ;
        case 4 :
        return "five" ;
        case 5 :
        return "six" ;
        case 6 :
        return "seven" ;
        case 7 :
        return "eight" ;
        case 8 :
        return "nine" ;
        case 9 :
        return "ten" ;
        case 10 :
        return "Jack" ;
        case 11 :
        return "Queen" ;
        case 12 :
        return "King" ;
        default :
        return "Unknown" ;
            }
    } //end of method getValueString

    // Other Card Methods

    /**
     * Resets the deck of cards to all undealt
     */
    public void restart()
    {
    for (int i = 0 ; i < 4 ; i++)
        for (int j = 0 ; j < 13 ; j++)
        dealt[i][j] = false ;
        noDealt = 0 ;
        } // end of method restart

    /**
     * return a string representing the card
     * @return details of the card ('value of suit')
     */
    public String toString()
        {
        return getValueString() + " of " + getSuitString() ;
        } // end of method toString

    /* public void setSuit(int s)
    {
    // s should be in the range 0 to 3
    if ((s < 0) || (s > 3)) suit = 0;
    else suit = s;
    } // end of method setSuit

    public void setValue(int v)
    {
    // value should be in the range 0 to 12
    if ((v < 0) || (v > 12)) value = 0;
    else value = v;
    } // end of method setValue */

    } // end of class card

2、需求一代码实现如下：

package cn.bdqn.demo04;

public class CardTest1 {

    public static void main(String[] args) {
        
        System.out.println("欢迎来到“21点”的扑克游戏！");
        int num=0;
        int sum=0;
        for (int i = 1; i <= 5; i++) {
            Card card=new Card();
            num=card.getValue()+1;
            System.out.println("第"+i+"张牌为:"+num);
            sum+=num;
        }

        System.out.println("现在的总点数为:"+sum);
        if(sum>21) {System.out.println("很遗憾，计算机赢，再接再厉！");}
        else  System.out.println("恭喜你，玩家赢！");
    }

}

3、需求二代码实现如下：

package cn.bdqn.demo04;

public class CardTest2 {

    public static void main(String[] args) {

        System.out.println("欢迎来到“21点”的扑克游戏！");
        int num = 0;
        int sum1 = 0;
        int sum2 = 0;
        // 为计算机抽牌
        System.out.println("计算机抽牌：");
        for (int i = 1; i <= 5; i++) {
            Card card = new Card();
            num = card.getValue() + 1;
            System.out.println("第" + i + "张牌为:" + num);
            sum1 += num;
        }
        System.out.println("计算机的总点数为:" + sum1);

        // 为用户抽牌
        System.out.println("用户抽牌：");
        for (int i = 1; i <= 5; i++) {
            Card card = new Card();
            num = card.getValue() + 1;
            System.out.println("第" + i + "张牌为:" + num);
            sum2 += num;
        }
        System.out.println("用户的总点数为:" + sum2);

        //判断
        if(sum1<=21&&sum2>21){
            System.out.println("很遗憾，计算机赢，再接再厉！");
        }else if(sum1<=21&&sum2<=21){
            System.out.println("很遗憾，双方都不算赢！");
        }else if(sum1>21&&sum2<=21){
            System.out.println("恭喜玩家赢！");
        }else{
            System.out.println("很遗憾，双方都超过21点！");
        }
    }

}

4、需求三代码实现如下：

package cn.bdqn.demo04;

import java.util.Scanner;

public class CardTest3 {

    public static void main(String[] args) {
        
        //键盘输入
        Scanner sc=new Scanner(System.in);
        
        System.out.println("欢迎来到“21点”的扑克游戏！");
        int num = 0;
        int sum1 = 0;
        int sum2 = 0;
        // 为计算机抽牌
        System.out.println("计算机抽牌：");
        for (int i = 1; i <= 5; i++) {
            Card card = new Card();
            num = card.getValue() + 1;
            System.out.println("第" + i + "张牌为:" + num);
            sum1 += num;
            if(sum1>21){
                break;
            }
        }
        System.out.println("计算机的总点数为:" + sum1);

        // 为用户抽牌
        System.out.println("请您输入1(抽牌)/0(不抽牌)选择是否抽牌：");
        int isNum=sc.nextInt();
        if(isNum==0){
            System.out.println("您选择了不抽牌，游戏结束！");
        }else if(isNum==1){
            System.out.println("用户抽牌：");
            for (int i = 1; i <= 5; i++) {
                Card card = new Card();
                num = card.getValue() + 1;
                System.out.println("第" + i + "张牌为:" + num);
                sum2 += num;
            }
            System.out.println("用户的总点数为:" + sum2);

            //判断
            if(sum1<=21&&sum2>21){
                System.out.println("很遗憾，计算机赢，再接再厉！");
            }else if(sum1<=21&&sum2<=21){
                System.out.println("很遗憾，双方都不算赢！");
            }else if(sum1>21&&sum2<=21){
                System.out.println("恭喜玩家赢！");
            }else{
                System.out.println("很遗憾，双方都超过21点！");
            }
        }else{
            System.out.println("选择错误，游戏结束！");
        }
    }
}

5、需求四代码实现如下：

package cn.bdqn.demo04;

import java.util.Scanner;

public class CardTest4 {

    public static void main(String[] args) {

        // 键盘输入
        Scanner sc = new Scanner(System.in);

        System.out.println("欢迎来到“21点”的扑克游戏！");

        // 默认初始值
        boolean flag = true;
        // 循环初始值
        int zeroNum = -1;
        // 用户赢牌总局数
        int userNums = 0;
        // 计算机赢牌总局数
        int comNums = 0;
        do {
            int num = 0;
            int sum1 = 0;
            int sum2 = 0;
            // 为计算机抽牌
            System.out.println("计算机抽牌：");
            for (int i = 1; i <= 5; i++) {
                Card card = new Card();
                num = card.getValue() + 1;
                System.out.println("第" + i + "张牌为:" + num);
                sum1 += num;
                if (sum1 > 21) {
                    break;
                }
            }
            System.out.println("计算机的总点数为:" + sum1);

            // 为用户抽牌
            boolean isChou = false;
            System.out.println("请您输入1(抽牌)/0(不抽牌)选择是否抽牌：");
            int isNum = sc.nextInt();
            if (isNum == 0) {
                System.out.println("您选择了不抽牌，游戏结束！");
                break;
            } else if (isNum == 1) {
                System.out.println("用户抽牌：");
                for (int i = 1; i <= 5; i++) {
                    Card card = new Card();
                    num = card.getValue() + 1;
                    System.out.println("第" + i + "张牌为:" + num);
                    sum2 += num;
                }
                System.out.println("用户的总点数为:" + sum2);

                // 判断
                if (sum1 <= 21 && sum2 > 21) {
                    userNums++;
                    System.out.println("计算机赢，总牌局数为：" + userNums);
                } else if (sum1 <= 21 && sum2 <= 21) {
                    System.out.println("很遗憾，双方都不算赢！");
                } else if (sum1 > 21 && sum2 <= 21) {
                    comNums++;
                    System.out.println("用户赢，总牌局数为：" + comNums);
                } else {
                    System.out.println("很遗憾，双方都超过21点！");
                }
            } else {
                System.out.println("选择错误，游戏结束！");
                break;
            }
            if (flag) {
                System.out.println("输入0返回游戏：");
                zeroNum = sc.nextInt();
            } else {

                break;
            }
        } while (zeroNum == 0);
    }
}

⛳️ 三、效果展示

1、需求一效果展示

2、需求二效果展示

3、需求三效果展示

4、需求四效果展示

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