if else

if

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();
        //判断字符串内容是否相等
        if(s.equals("hello")){
            System.out.println("s = " + s);
        }
        System.out.println("end..");
        scanner.close();
    }
}

if else

public class IfDemo02 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入成绩");
        int i = scanner.nextInt();
        if(i>60){
            System.out.println("及格！");
        }else {
            System.out.println("不及格！");
        }
        scanner.close();
    }
}

if 多重else if

public class IfDemo03 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入成绩");
        int i = scanner.nextInt();
        if(i==100){
            System.out.println("满分！");
        }else if(i<100 && i>=80){
            System.out.println("优秀！");
        } else if(i<80 && i>=60){
            System.out.println("及格！");
        } else if(i<60){
            System.out.println("不及格！");
        } else {
            System.out.println("成绩不合法！");
        }
        scanner.close();
    }
}