✅作者简介：热爱国学的Java后端开发者，修心和技术同步精进。
?个人主页：乐趣国学的博客
?个人信条：不迁怒，不贰过。小知识，大智慧。
?当前专栏：Java案例分享专栏
✨特色专栏：国学周更-心性养成之路
?本文内容：Java——“21点”扑克游戏系统（变量+循环）
更多内容点击?
Java——对象和类案例代码详解
目录
⛳️ 一、项目需求
⛳️ 二、代码实现
⛳️ 三、效果展示
⛳️ 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 3if ((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 12if ((v < 0) || (v > 12)) value = 0;else value = v;} // end of method setValue */ } // end of class card2、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
码文不易，本篇文章就介绍到这里，如果想要学习更多Java系列知识，请关注博主，博主带你零基础学习Java知识。与此同时，对于日常生活有困扰的朋友，欢迎阅读我的第四栏目：《国学周更—心性养成之路》，学习技术的同时，我们也注重了心性的养成。
