SimpleDateFormat returning incorrect day on given date

I was recently doing a question on HackerRank in which I was asked to find the day on a given date. I used SimpleDateFormat to find the day.

Below is my code:

String sd = Integer.toString(day) + "-" + Integer.toString(month) + "-" + Integer.toString(year);
try {
	Date d = new SimpleDateFormat("DD-MM-yyyy").parse(sd);
	SimpleDateFormat sdf = new SimpleDateFormat("EEEE");
	return sdf.format(d).toUpperCase();
} catch (Exception e) {
	return "";
}

The funny thing here is that the above code is printing correct result for today's date i.e. 03/04/2020(Friday) but it is returning incorrect day on 05/08/2015(it should return Wednesday but instead it returns Monday).

Please help me to find the problem.

Thank you.

EDIT
I was doing a little mistake that I wanted to use the day of the month, for which dd has to be used. DD represents the day of the year. That solved my problem!

You should be using SimpleDateFormat("dd-MM-yyyy").

DD is for day in year, like there are 365 days in a year.

The cause of the problem is using DD instead of dd.

I also suggest you not to use the outdated date/time API e.g. java.util.Date and SimpleDateFormat. Instead, you should use the modern date/time API e.g. types from the packages, java.time and java.time.format as shown below:

import java.time.DayOfWeek;
import java.time.LocalDate;
import java.time.format.TextStyle;
import java.util.Locale;

public class Main {
    public static void main(String[] args) {
        int day = 5;
        int month = 8;
        int year = 2010;
        LocalDate date = LocalDate.of(year, month, day);
        DayOfWeek dayOfWeek = date.getDayOfWeek();
        System.out.println(dayOfWeek);
        System.out.println(dayOfWeek.getDisplayName(TextStyle.FULL, Locale.US));
        System.out.println(dayOfWeek.getDisplayName(TextStyle.SHORT, Locale.US));
    }
}

Output:

THURSDAY
Thursday
Thu

Using DateTimeFormatter:

import java.time.DayOfWeek;
import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.time.format.TextStyle;
import java.util.Locale;

public class Main {
	public static void main(String[] args) {
		int day = 5;
		int month = 8;
		int year = 2010;
		String sd = String.format("%02d", day) + "-" + String.format("%02d", month) + "-" + String.format("%04d", year);
		DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd-MM-yyyy");
		LocalDate date = LocalDate.parse(sd, formatter);
		DayOfWeek dayOfWeek = date.getDayOfWeek();
		System.out.println(dayOfWeek);
		System.out.println(dayOfWeek.getDisplayName(TextStyle.FULL, Locale.US));
		System.out.println(dayOfWeek.getDisplayName(TextStyle.SHORT, Locale.US));
	}
}

Output:

THURSDAY
Thursday
Thu