JAVASE精密逻辑控制过程详解(分支和循环语句)

System.out.println("aaa");
System.out.println("bbb");
System.out.println("ccc");
// 运行结果
aaa
bbb
ccc

if(布尔表达式){
// 语句
}

if(布尔表达式){
// 语句1
}else{
// 语句2
}

int score = 92;
if(score >= 90){
    System.out.println("吃个大鸡腿!!!");
}else{
    System.out.println("挨大嘴巴子!!!");
}

if(布尔表达式1){
// 语句1
}else if(布尔表达式2){
// 语句2
}else{
// 语句3
}

if(score >= 90){
    System.out.println("优秀");
}else if(score >= 80 && score < 90){
    System.out.println("良好");
}else if(score >= 70 && score < 80){
    System.out.println("中等");
}else if(score >= 60 && score < 70){
    System.out.println("及格");
}else if(score >= 0 && score < 60){
    System.out.println("不及格");
}else{
    System.out.println("错误数据");
}

int day = 1;
switch(day) {
    case 1:
        System.out.println("星期一");
        break;
    case 2:
        System.out.println("星期二");
        break;
    case 3:
        System.out.println("星期三");
        break;
    case 4:
        System.out.println("星期四");
        break;
    case 5:
        System.out.println("星期五");
        break;
    case 6:
        System.out.println("星期六");
        break;
    case 7:
        System.out.println("星期日");
        break;
    default:
        System.out.println("输入有误");
        break;
}

double num = 1.0;
switch(num) {
    case 1.0:
        System.out.println("hehe");
        break;
    case 2.0:
        System.out.println("haha");
        break;
}

// 编译出错
Test.java:4: 错误: 不兼容的类型: 从double转换到int可能会有损失
switch(num) {
^
1 个错误

int day = 1;
switch(day) {
case 1:
System.out.println("星期一");
// break;
case 2:
System.out.println("星期二");
break;
}
// 运行结果
星期一
星期二

int num = 1;
while (num <= 10) {
    System.out.println(num);
    num++;
}

int result = 1;
for (int i = 1; i <= 5; i++) {
    result *= i;
}
System.out.println("result = " + result);

int num = 1;
do {
    System.out.println(num);
    num++;
} while (num <= 10);

int num = 100;
while (num <= 200) {
    if (num % 3 == 0) {
        System.out.println("找到了 3 的倍数, 为:" + num);
        break;
    }
    num++;
}
// 执行结果
//找到了 3 的倍数, 为:102

int num = 100;
while (num <= 200) {
    if (num % 3 != 0) {
        num++; // 这里的 ++ 不要忘记! 否则会死循环.
        continue;
    }
    System.out.println("找到了 3 的倍数, 为:" + num);
    num++;
}

import java.util.Scanner; // 需要导入 util 包
Scanner sc = new Scanner(System.in);
System.out.println("请输入你的姓名：");
String name = sc.nextLine();
System.out.println("请输入你的年龄：");

int age = sc.nextInt();
System.out.println("请输入你的工资：");
float salary = sc.nextFloat();
System.out.println("你的信息如下：");
System.out.println("姓名: "+name+"\n"+"年龄："+age+"\n"+"工资："+salary);
sc.close(); // 注意, 要记得调用关闭方法

Scanner sc = new Scanner(System.in);
int sum = 0;
int num = 0;
while (sc.hasNextInt()) {
    int tmp = sc.nextInt();
    sum += tmp;
    num++;
}
System.out.println("sum = " + sum);
System.out.println("avg = " + sum / num);
sc.close();//关闭new打开的类

import java.util.Random;
import java.util.Scanner;;
class Test {
    public static void main(String[] args) {
        Random random = new Random(); // 默认随机种子是系统时间
        Scanner sc = new Scanner(System.in);
        int toGuess = random.nextInt(100);
        // System.out.println("toGuess: " + toGuess);
        while (true) {
            System.out.println("请输入要输入的数字: (1-100)");
            int num = sc.nextInt();
            if (num < toGuess) {
                System.out.println("低了");
            } else if (num > toGuess) {
                System.out.println("高了");
            } else {
                System.out.println("猜对了");
                break;
            }
        }
    sc.close();
    }
}