一、分支结构

1、分支结构

补充：怎么从键盘中获取不同类型的变量

import java.util.Scanner; class Structure{ public static void main(String[] args){ //从键盘获取变量，实例化 Scanner scan =new Scanner(System.in); System.out.println("输入姓名"); String name=scan.next(); System.out.println(name); System.out.println("输入年龄"); int age=scan.nextInt(); System.out.println(age); System.out.println("输入体重"); double weight=scan.nextDouble(); System.out.println(weight); System.out.println("是否单身"); boolean single=scan.nextBoolean(); System.out.println(single); } }

如何获取随机数

2、switch-case

class Structure{ public static void main(String[] args){ int value = 15; switch(value){ case 11: System.out.println(11); break; case 15: System.out.println(15); break; default: System.out.println("others"); } } }

二、循环结构

1、for循环

import java.util.Scanner; class Structure{ public static void main(String[] args){ Scanner scan = new Scanner(System.in); System.out.println("输入两个正整数，回车键隔开"); int m = scan.nextInt(); int n = scan.nextInt(); //最小公倍数 for (int i=1; i<m*n; i++){ if (i*m%n==0){ System.out.println("最小公倍数："+i*m); break; } } //最大公约数 int min = (m>n) ? n : m; for (int i=min; i>0; i--){ if (n%i==0 & m%i==0){ System.out.println("最大公约数："+i); break; } } } }

2、while 循环

import java.util.Scanner; class Structure{ public static void main(String[] args){ Scanner scan = new Scanner(System.in); System.out.println("输入两个正整数，回车键隔开"); int m = scan.nextInt(); int n = scan.nextInt(); //最小公倍数 int i=1; while (i<m*n){ if (i*m%n==0){ System.out.println("最小公倍数："+i*m); break; } i++; } //最大公约数 int min = (m>n) ? n : m; int j=min; while (j>0){ if (n%j==0 & m%j==0){ System.out.println("最大公约数："+j); break; } j--; } } }

3、do-while循环

for(; ;) 和 while(true)一个含义

补充：计算0-100的所有质数

import java.util.Scanner; class Structure{ public static void main(String[] args){ Scanner san = new Scanner(System.in); int num = 100; for (int i=2;i<=num;i++){ boolean isFlag = true; for (int j = 2;j < Math.sqrt(i);j++){ if (i%j==0){ isFlag = false; break; } } if (isFlag == true){ System.out.println(i); } } } }

三、break和continue