一些基础的java编程代码

Java基础代码

文章目录

• JAVA基础代码
• • 1、强制类型转换
  • 2、判断是否为闰年
  • 3、交换数字
  • 4、单价，数量，金额，满500打8折
  • 5、生成随机数并猜数
  • 6、乘法表
  • 8、打印
  • 9、奇数偶数和
  • 10、1000内被5整除的数
  • 11、9的阶乘
  • 12、素数的查找（开平方版）
  • 13随机数，Math版
  • 14、月份，年份查询
  • 15、Switch版成绩查询
  • 16、打印菱形（新）

1、强制类型转换

public class Day1 {//强制类型转换public static void main(String[] args) {byte a = (byte) 257; //超出最大额度强制类型转换会从头开始计数System.out.println(a);}

2、判断是否为闰年

//判断是否为闰年 闰年要能取余4但是不能取余100，取余400的也可以@Testpublic void work1() {Scanner scanner = new Scanner(System.in);int year = scanner.nextInt();if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0) {System.out.println("是闰年");} else {System.out.println("是平年");}}

3、交换数字

@Testpublic void work2() {int a, b, c;Scanner scanner = new Scanner(System.in);a = scanner.nextInt();b = scanner.nextInt();System.out.println("数字1是：" + a + " 数字是2：" + b);c = a;a = b;b = c;System.out.println("数字1是：" + a + " 数字2是：" + b);}

4、单价，数量，金额，满500打8折

@Testpublic void work3() {int b;double a, c, d, e;Scanner scanner = new Scanner(System.in);System.out.println("请输入单价");a = scanner.nextDouble();System.out.println("请输入数量");b = scanner.nextInt();System.out.println("请输入金额");c = scanner.nextDouble();if (a * b >= 500) {d = a * b * 0.8;if (d > c) {System.out.println("钱不够哦，亲");return;}} else {d = a * b;if (d > c) {System.out.println("钱不够哦，亲");return;}}e = c - d;System.out.println("应收金额 " + d + " 找零 " + e);}

5、生成随机数并猜数

@Testpublic void work4() {int random = new Random().nextInt(1000);int caice = 0;Scanner scanner = new Scanner(System.in);while (scanner.hasNextInt()) {caice = scanner.nextInt();if (caice > random) {System.out.println("大了");} else if (caice < random) {System.out.println("小了");}if (caice == random) {System.out.println("随机数为" + random);System.exit(0);//退出循环}}System.out.println("结束");}

6、乘法表

@Testpublic void work5() {for (int i = 1; i <= 9; i++) {for (int j = 1; j <= i; j++) {int sum = i * j;System.out.print(i + "*" + j + "=" + sum + " ");if (i == j)System.out.println();}}}```## 7、年份，硬写版，实际上31天的可以放一起用一个break 例如case1： case3： break;                   ```java@Testpublic void work6() {int i;Scanner scanner = new Scanner(System.in);i = scanner.nextInt();switch (i) {case 1:System.out.println("1月有31天");break;case 2:System.out.println("2月有28/29天");break;case 3:System.out.println("3月有31天");break;case 4:System.out.println("4月有30天");break;case 5:System.out.println("5月有31天");break;case 6:System.out.println("6月有30天");break;case 7:System.out.println("7月有31天");break;case 8:System.out.println("8月有31天");break;case 9:System.out.println("9月有30天");break;case 10:System.out.println("10月有31天");break;case 11:System.out.println("11月有30天");break;case 12:System.out.println("12月有31天");break;default:break;}}

8、打印

//打印1到12345@Testpublic void work7() {int i, j;for (i = 1; i <= 5; i++) {for (j = 1; j <= i; j++) {System.out.print(j);if (i == j) {System.out.println();}}}}//打印菱形笨办法，可以打印空格，然后打印*号@Testpublic void work8() {for (int i = 1; i <= 6; i++) {//每行打印的空格数for (int j = 6; j >= i; j--) {System.out.print(" ");}//打印左半边的*for (int j = 1; j <= i; j++) {System.out.print("*");}//打印右半边的*,因为此时第一行不用打印*,所以,jfor (int j = 1; j < i; j++) {System.out.print("*");}System.out.println();}}

9、奇数偶数和

@Testpublic void work9() {int sum1 = 0, sum2 = 0, i;for (i = 1; i <= 100; i++) {if (i % 2 == 0) {sum2 = sum2 + i;} else {sum1 = sum1 + i;}}System.out.println("奇数和 =" + sum1 + "偶数和 =" + sum2);}

10、1000内被5整除的数

@Testpublic void work10() {int i, flag = 0;for (i = 1; i <= 1000; i++) {if (i % 5 == 0) {System.out.print(i + " ");flag++;if (flag == 3) {flag = 0;System.out.println();}}}}

11、9的阶乘

@Testpublic void work11() {int sum = 1;for (int i = 9; i >= 1; i--) {sum = sum * i;if (i != 1) {System.out.print(i + "*");}if (i == 1) {System.out.println(i + "=" + sum);}}}

12、素数的查找（开平方版）

@Testpublic void work12() {int i, j, count = 0;for (i = 100; i <= 200; i++) {for (j = 2; j <= Math.sqrt(i); j++) {if (i % j == 0) {break;}}if (j > Math.sqrt(i)) {System.out.println(i + " ");count++;}}System.out.println("素数的个数为 " + count + "个");}

13随机数，Math版

@Testpublic void work13() {int random = (int) (Math.random() * 1000 + 1);System.out.println(random);Scanner scanner = new Scanner(System.in);System.out.println("请输入猜测: ");while (scanner.hasNextInt()) {int a = scanner.nextInt();if (a == 0) {System.out.println("程序退出");break;}if (a > 1000 || a < 0) {System.out.println("请输入合法数据");continue;}if (a > random) {System.out.println("太大了");} else if (a < random) {System.out.println("太小了");} else if (a == random) {System.out.println("恭喜你，猜对了！ 随机数是 " + random);System.exit(0);}}}

14、月份，年份查询

@Testpublic void work14() {Scanner scanner = new Scanner(System.in);System.out.println("请依次输入年份，月份");int year = scanner.nextInt();int month = scanner.nextInt();int flag = 0;if (year % 4 == 0 && year % 100 != 0 || year % 400 == 0) {System.out.println("是闰年");flag = 1;} else {System.out.println("是平年");flag = 0;}if (month == 2 && flag == 1) {month = 13;}switch (month) {case 1:System.out.println("1月有31天");break;case 2:System.out.println("2月有28");break;case 3:System.out.println("3月有31天");break;case 4:System.out.println("4月有30天");break;case 5:System.out.println("5月有31天");break;case 6:System.out.println("6月有30天");break;case 7:System.out.println("7月有31天");break;case 8:System.out.println("8月有31天");break;case 9:System.out.println("9月有30天");break;case 10:System.out.println("10月有31天");break;case 11:System.out.println("11月有30天");break;case 12:System.out.println("12月有31天");break;case 13:System.out.println("2月有29天");break;default:break;}}

15、Switch版成绩查询

@Testpublic void work15() {Scanner scanner = new Scanner(System.in);int score = scanner.nextInt();if (score < 0 || score > 100) {System.out.println("非法数据!");return;}switch (score / 10) {case 9:case 10:System.out.println("优秀");break;case 8:System.out.println("良好");break;case 7:System.out.println("一般");break;case 6:System.out.println("及格");break;default:System.out.println("不及格");break;}}

16、打印菱形（新）

@Testpublic void zifu() {for (int i = 1; i <=6 ; i++) {for(int j=1;j<=(6-i);j++){System.out.print(" ");}for(int j=1;j<=(2*i-1);j++){System.out.print("*");}System.out.println();}}}

来源地址：https://blog.csdn.net/qq_51114085/article/details/125751745