随机验证码
package com.fan.caseExercise;import java.util.Random;public class Demo01 {public static void main(String[] args) {String code = createCode(5); //输入你想要的验证码位数System.out.println(code);}public static String createCode(int n){//1.定义一个for循环，用于控制产生多少位随机字符Random random = new Random();//3.定义一个String类型的变量，用于记忆产生的每位随机字符String code = "";for (int i = 1; i <= n; i++) {//2.为每一个位置生成一个随机字符int r = random.nextInt(3); //随机一个 0 1 2 ，0代表随机数字；1 2代表随机大小写字母switch (r){case 0://随即一个数字code += random.nextInt(10);break;case 1://随机一个大写字母 A 65 Z 65+25 （0-25）+ 65char ch1 = (char) (random.nextInt(26) + 65);code += ch1;break;case 2://随机一个小写字母 a 97 z 97+25char ch2 = (char) (random.nextInt(26) + 97);code += ch2;break;}}return code;}
}
评委打分
package com.fan.caseExercise;import java.util.Scanner;public class Democracy {public static void main(String[] args) {Scanner scanner = new Scanner(System.in);System.out.println("请输入评委的人数：");int count = scanner.nextInt();//引用方法 （直接输出引用）System.out.println(arvergeScore(count));}public static double arvergeScore (int num) {//接收评委打分int[] score = new int[num];for (int i = 0; i < score.length; i++) {System.out.println("请输入第" + (i+1) + "个评委的打分：");Scanner scanner1 = new Scanner(System.in);int score1 = scanner1.nextInt();score[i] = score1;}//冒泡排序 （升序）int x =0;for (int i = 0; i < score.length; i++) {for (int j = 0; j < score.length - 1; j++) {if (score[j] > score[j+1]){x = score[j];score[j] = score[j+1];score[j+1] = x;}}}//舍去极端值，求平均数double sum = 0;for (int i = 0; i < score.length - 1; i++) {if (i != 0){sum += score[i];}}//返回结果//return sum;return 1.0 * (sum / (score.length - 2));}
}
数字加密
package com.fan.caseExercise;import java.util.Scanner;public class Demo03 {public static void main(String[] args) {int[] code = new int[4];System.out.println("请依次输入您的四位数密码：");//对Scanner使用for循环捕捉键盘上的数据并依次交给code数组for (int i = 0; i <= 3; i++) {Scanner scanneri = new Scanner(System.in);code[i] = scanneri.nextInt();}//遍历加密后的数组for (int i:enc(code)){System.out.print(i + "\t");}}public static int[] enc (int[] array) {int[] x = new int[array.length];//承接加密后的密码int j = array.length-1;//加密for (int i = 0; i < array.length; i++) {if (j>=0){x[j] = (array[i] + 5) % 10; //对code数组中的每个数字进行+5 再对10求余 最后反转j--;}}//返回加密后的密码xSystem.out.println("-------------");return x;}
}
精简优化版
package com.fan.caseExercise;import java.util.Scanner;public class Demo03 {public static void main(String[] args) {int[] code = new int[4];System.out.println("请依次输入您的四位数密码：");//对Scanner使用for循环捕捉键盘上的数据并依次交给code数组for (int i = 0; i <= 3; i++) {Scanner scanneri = new Scanner(System.in);code[i] = scanneri.nextInt();}//遍历加密后的数组for (int i:enc(code)){System.out.print(i + "\t");}}public static int[] enc (int[] array) {int[] x = new int[array.length];//承接加密后的密码//加密for (int i = 0, j = array.length-1; i < array.length && j>=0; i++,j--) {x[j] = (array[i] + 5) % 10; //对code数组中的每个数字进行+5 再对10求余 最后反转}//返回加密后的密码xSystem.out.println("-------------");return x;}
}
抽红包
1.0版本（多损耗性能）
package com.fan.caseExercise;import java.util.Random;
import java.util.Scanner;public class Demo04 {public static void main(String[] args) {//设立奖池int[] moneys = {9,666,188,520,99999};//调用抽奖方法draw(moneys);}public static void draw (int[] arr){Scanner sc = new Scanner(System.in);System.out.println("请输入任意符号开始抽奖！");//抽5次奖for (int i = 1; i <= 5; i++) {sc.next(); //Enter进行下一步操作 模拟抽奖开始按钮while (true) {Random r = new Random();int index = r.nextInt(arr.length);if (arr[index] != 0) { //若等于0表示轮空，系统内部重新抽奖System.out.println("您的中奖金额为：" + arr[index]);arr[index] = 0; //刷新奖池break; //结束本次抽奖}}}System.out.print("--------------" + "\n" + "奖池已瓜分完毕！");}
}
2.0版本（利用换牌算法实现）
package com.fan.caseExercise;import java.util.Random;
import java.util.Scanner;public class Demo05 {public static void main(String[] args) {//设立奖池int[] moneys = {9,666,188,520,99999};//调用抽奖方法draw(moneys);}public static void draw (int[] arr){//洗牌算法（换牌算法）//每次让数组中第 n=arr.length-1 (n--)元素与任意一个元素互换//（包括自己与自己互换）(互换后锁定最后一个元素)for (int i = arr.length-1; i > 0; i--) { //选取数组中最后一个元素Random r = new Random();int j = r.nextInt(i+1); //从下标（0~i）中随机选取一个元素//arr[i]与arr[j]互换int temp = arr[i];arr[i] = arr[j];arr[j] = temp;}Scanner sc = new Scanner(System.in);System.out.println("请输入任意字符并按下Enter键开始抽奖！");for (int i = 0; i < arr.length; i++) {sc.next(); //模拟用户开始抽奖交互按钮System.out.print("您的中奖金额为：" + arr[i] + "\n-----------------\n");}System.out.println("奖池已瓜分完毕！");}
}
找质数
package com.fan.caseExercise;public class Demo06 {public static void main(String[] args) {System.out.println(prim(101,200));}public static int prim (int start,int end){int count = 0;OUT:for (int i = start; i <= end ; i++) {for (int j = 2; j <= Math.sqrt(i); j++) {if (i % j == 0){continue OUT;}}System.out.println(i);count++;}System.out.println("质数的个数为：");return count;}
}
双色球
package com.fan.caseExercise;import java.util.Random;
import java.util.Scanner;public class Demo07 {public static void main(String[] args) {int[] user = DCB();int[] lucy = creatLucyNumbers();System.out.print("您的号码为：\t");PrintArray(user);System.out.print("中奖号码为：\t");PrintArray(lucy);System.out.print("中奖情况为：\t");judge(user,lucy);}//打印数组public static void PrintArray(int[] arr) {System.out.print("[");for (int i = 0; i < 7; i++) {System.out.print(i == 6 ? arr[i] : arr[i] + ",");}System.out.println("]");}//读取用户输入的双色球号码public static int[] DCB (){int[] dbc= new int[7];Scanner sc = new Scanner(System.in);Scanner sc1 = new Scanner(System.in);//红球for (int i = 0; i < 6; i++) {while (true) {System.out.println("请输入第"+(i+1)+"个红球号码（1~33）：");int num = sc.nextInt();if (num < 1 || num > 33) {System.out.println("号码超出范围，请重新输入！");}else {if (chRe(dbc,num)){dbc[i] = num;break;}else {System.out.println("号码重复，请重新输入！");}}}}//蓝球while (true) {System.out.println("请输入蓝球号码（1~16）：");int num = sc1.nextInt();if (num < 1 || num > 16) {System.out.println("号码超出范围，请重新输入！");} else {dbc[6] = num;break;}}return dbc;}//检查号码是否重复(T代表不重复)public static boolean chRe (int[] arr,int number){boolean x = true;for (int i = 0; i < 6; i++) {if (arr[i] == 0){return x;}if (arr[i] == number){x = false;return x;}}return x;}//生成随机中奖号码public static int[] creatLucyNumbers(){Random r = new Random();int[] Lucys= new int[7];//随机红球号码for (int i = 0; i < Lucys.length - 1; i++) {while (true) {int LucyNumber = r.nextInt(33) + 1;if (chRe(Lucys, LucyNumber)) {Lucys[i] = LucyNumber;break;}}}//随机蓝球号码Lucys[6] = r.nextInt(16) + 1;;return Lucys;}//检查中奖情况public static void judge(int[] userNUmbers,int[] lucyNumbers){int redcount = 0;int bluecount = 0;//判断红球中奖数量for (int i = 0; i < userNUmbers.length - 1; i++) {for (int j = 0; j < lucyNumbers.length - 1; j++) {if (userNUmbers[i] == lucyNumbers[j]){redcount++;break;}}}//判断蓝球是否命中bluecount = userNUmbers[6] == lucyNumbers[6] ? 1 : 0;//判断中奖情况if (bluecount == 1){switch (redcount){case (6):System.out.println("恭喜中奖，金额为：10000000元！");break;case (5):System.out.println("恭喜中奖，金额为：3000元！");break;case (4):System.out.println("恭喜中奖，金额为：200元！");break;case (3):System.out.println("恭喜中奖，金额为：10元！");break;case (2):case (1):case (0):System.out.println("恭喜中奖，金额为：5元！");break;}}else {switch (redcount){case (6):System.out.println("恭喜中奖，金额为：5000000元！");break;case (5):System.out.println("恭喜中奖，金额为：200元！");break;case (4):System.out.println("恭喜中奖，金额为：10元！");break;case (3):case (2):case (1):case (0):System.out.println("没中~~~");}}}
}
