if：if...else...及if嵌套
提示用户输入三个整数，判断并输出最大值、最小值
package com.qzcsbj;
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.print("请依次输入第一个整数：");
int a = input.nextInt();
System.out.print("请依次输入第二个整数：");
int b = input.nextInt();
System.out.print("请依次输入第三个整数：");
int c = input.nextInt();
int max, min;
if (a > b) {
max = a;
min = b;
} else {
max = b;
min = a;
}
if (c > max) {
max = c;
}
if (c < min) {
min = c;
}
System.out.println("最大值：" + max);
System.out.println("最小值：" + min);
}
}
如果今天是周日且晴天，就出去嗨
如果今天是周日但不是晴天，睡懒觉
如果今天不是周日，继续996
说明：天气等变量，自己定义即可；主要练习if嵌套
package com.qzcsbj;
/**
* @描述 : <>
*/
public class Test {
public static void main(String[] args) {
int today=0;
String weather="晴天";
if(today==0){
if(weather=="晴天"){
System.out.println("今天周末，出去嗨");
}else{
System.out.println("今天休息，家里睡懒觉");
}
}else{
System.out.println("继续996");
}
}
}
由键盘输入三个整数分别存入变量num1、num2、num3，对它们进行排序(使用 if-else if-else)，并且从小到大输出。
package com.qzcsbj;
import java.util.Scanner;
/**
* @描述 : <>
*/
public class Test {
public static void main(String[] args) {
System.out.println("请输入三个整数.");
Scanner scanner = new Scanner(System.in);
System.out.print("num1=");
int num1 = scanner.nextInt();
System.out.print("num2=");
int num2 = scanner.nextInt();
System.out.print("num3=");
int num3 = scanner.nextInt();
System.out.println("您输入的三个整数分别为: " + num1 + ", " + num2 + ", " + num3);
if(num1 <= num2){
if(num3 <= num1){
System.out.println(num3 + ", " + num1 + ", " + num2);
}else if(num3 >= num2){
System.out.println(num1 + ", " + num2 + ", " + num3);
}else{
System.out.println(num1 + ", " + num3 + ", " + num2);
}
}else{
if(num3 <= num2){
System.out.println(num3 + ", " + num2 + ", " + num1);
}else if(num3 >= num1){
System.out.println(num2 + ", " + num1 + ", " + num3);
}else{
System.out.println(num2 + ", " + num3 + ", " + num1);
}
}
}
}
提示用户输入三角形的边a、b、c，范围必须在 [1,100) 之间，判断三角形的类型：1.非三角形；2.等边三角形；3.直角三角形；4.等腰三角形；5.普通三角形
package com.qzcsbj;
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.print("请输入第一个边：");
int a = input.nextInt();
System.out.print("请输入第二个边：");
int b = input.nextInt();
System.out.print("请输入第三个边：");
int c = input.nextInt();
if (a < 1 || a >= 100 || b < 1 || b >= 100 || c < 1 || c >= 100) {
System.out.println("数据无效！");
} else {
if (a + b <= c || a + c <= b || b + c <= a) {
System.out.println("非三角形！");
} else {
if (a == b && a == c) {
System.out.println("等边三角形！");
} else if (a * a + b * b == c * c || a * a + c * c == b * b
|| b * b + c * c == a * a) {
System.out.println("直角三角形！");
}else if(a==b || a==c || b==c){
System.out.println("等腰三角形！");
}else{
System.out.println("普通三角形！");
}
}
}
}
}
switch
周一跑步，周二、三、四打羽毛球，周五游泳，其它休息
int today=4;
package com.qzcsbj;
public class Test {
public static void main(String[] args) {
int today=4;
switch(today){
case 1:
System.out.println("今天跑步");
break;
case 2:
case 3:
case 4:
System.out.println("今天打羽毛球");
break;
case 5:
System.out.println("今天游泳");
break;
default:
System.out.println("今天休息");
}
System.out.println("switch之后的代码");
}
}
输入 2022 年的某个月份和日期，例如 month=4，day=21，经过程序计算，打印出输入的月份和日期是 2022年的第几天：31+28+31+21
package com.qzcsbj;
import java.util.Scanner;
/**
* @描述 : <>
*/
public class Test {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("month: ");
int month = scanner.nextInt();
System.out.print("day: ");
int day = scanner.nextInt();
int days = day;
switch(month - 1){
case 11:
days += 30;
case 10:
days += 31;
case 9:
days += 30;
case 8:
days += 31;
case 7:
days += 31;
case 6:
days += 30;
case 5:
days += 31;
case 4:
days += 30;
case 3:
days += 31;
case 2:
days += 28;
case 1:
days += 31;
}
System.out.println(month + "月" + day + "日是 2022 年的第" + days + "天");
}
}
__EOF__
本文作者：持之以恒（韧）