Java流程控制:if选择结构

package pro.xiaoqian.struct;

import java.util.Scanner;

public class ifDemo01 {
    public static void main(String[] args) {
        Scanner scaner = new Scanner(System.in);
        System.out.println("请输入一个内容");
        String s = scaner.nextLine();

        //equals:判断字符串是否相等
        if (s.equals("Hello")){
            System.out.println(s);
        }
        System.out.println("End");
        scaner.close();
    }
}

运行结果

package pro.xiaoqian.struct;

import java.util.Scanner;

public class ifDemo02 {
    public static void main(String[] args) {
        //考试分数大于60即使及格,小于60分就不及格.
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入成绩:");
        int score = scanner.nextInt();

        
        if(score>60){
            System.out.println("及格");
        }else{
            System.out.println("不及格");
        }
        scanner.close();

    }
}

运行结果

if语句至多有一个else语句,else语句在所有的else if语句之后

if语句可以有若干个else if 语句,他们必须在else语句之前

一旦其中一个else if 语句检测为true,其它的else if 以及else 语句都将跳过执行

package pro.xiaoqian.struct;

import java.util.Scanner;

public class ifDemo03 {
    public static void main(String[] args) {
        //考试分数大于60即使及格,小于60分就不及格.
        Scanner scanner = new Scanner(System.in);
        


        System.out.println("请输入成绩:");
        int score = scanner.nextInt();


        if(score==100){
            System.out.println("恭喜满分");
        }else if (score<100 && score>=90){
            System.out.println("A级");
        }else if (score<90&& score>=80){
            System.out.println("B级");
        }else if (score<80 && score>=70){
            System.out.println("C级");
        }else if (score<70 && score>=60){
            System.out.println("D级");
        }else if (score<60 && score>=0){
            System.out.println("不及格");
        }else{
            System.out.println("成绩不合法");
        }
        scanner.close();

    }
}

运行结果