Java选择结构

package github.struct;

import java.util.Scanner;

/**
 * @author subeiLY
 * @create 2021-05-26 14:30
 */
public class IFDemo01 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.println("请输入内容:");
        String s = scanner.nextLine();

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

        System.out.println("End");

        scanner.close();
    }
}

package github.struct;

import java.util.Scanner;

/**
 * @author subeiLY
 * @create 2021-05-26 14:36
 */
public class IFDemo02 {
    public static void main(String[] args) {
        // 考试分数大于60就是及格，小于60则为不及格
        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();
    }
}

package github.struct;

import java.util.Scanner;

/**
 * @author subeiLY
 * @create 2021-05-26 14:41
 */
public class IFDemo03 {
    public static void main(String[] args) {
        // 考试分数大于60就是及格，小于60则为不及格
        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();
    }
}

package github.struct;

import java.util.Scanner;

/**
 * @author subeiLY
 * @create 2021-05-26 14:48
 */
public class IFDemo04 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        //
        char grade = 'K';
        switch (grade){
            case 'A':
                System.out.println("优秀");
                break;
            case 'B':
                System.out.println("良好");
                break;
            case 'C':
                System.out.println("及格");
                break;
            case 'D':
                System.out.println("再接再厉");
                break;
            case 'E':
                System.out.println("挂科");
                break;
            default:
                System.out.println("成绩错误！！！");
        }

        scanner.close();
    }
}