If选择结构

package Struck;

import java.util.Scanner;

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();
    }
}

=======================================================================================

import java.util.Scanner;

public class IfDemo02 {
    public static void main(String[] args) {
        //分数大于等于60为及格，小于60分数不及格
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入分数：");
        int score = scanner.nextInt();

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

=======================================================================================

package Struck;

import java.util.Scanner;

public class IfDemo03 {
    public static void main(String[] args) {
        //分数大于等于60为及格，小于60分数不及格
        Scanner scanner = new Scanner(System.in);
        /**
         * if语句至少有一个else语句，else语句在所有的else if语句之后
         * if语句可以有多个else if语句，他们必须在else语句之前
         * 当其中一个else if语句为true时，其他的else if以及else语句都将跳过执行
         */
        System.out.println("请输入分数：");
        int score = scanner.nextInt();

        if (score==100) {
            System.out.println("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("错误成绩");
        }
        scanner.close();
    }
}

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