calendar.getDisplayName 返回错误的日期

Below is my program and it is returning the wrong day name when I enter the related month, date and year.

我在这里缺少什么?

我的计划

import java.util.Calendar;
import java.util.Locale;
import java.util.Scanner;

public class TimeTest {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String month = in.next();
        String day = in.next();
        String year = in.next();

        System.out.println(getDay(day, month, year));
    }

    private static String getDay(String day, String month, String year) {
        Calendar calendar = Calendar.getInstance();
        calendar.set(Integer.parseInt(year), Integer.parseInt(month), Integer.parseInt(day));
        return calendar.getDisplayName(Calendar.DAY_OF_WEEK, Calendar.LONG, Locale.getDefault());

    }
}      

输出:

09
24
2018
Wednesday       

它应该返回星期一"，因为那是当天.

08 // September Month not August
24
2018