public class Day {

	private int year;
	private int month;
	private int day;

	// Constructors

	public Day(int y, int m, int d) {
		this.year = y;
		this.month = m;
		this.day = d;
	}

	public Day(int y) {
		this(y, 1, 1);
	}

	public Day(int y, int nth_dayInYear) {
		this.year = y;
		int dPassed = 0;
		int m = 1;
		while (dPassed + getMonthTotalDays(y, m) < nth_dayInYear) {
			dPassed += getMonthTotalDays(y, m);
			m++;
		}
		this.month = m;
		this.day = nth_dayInYear - dPassed;
	}

	private static int getMonthTotalDays(int y, int m) {
		int d = 31;
		while (valid(y, m, d) == false) {
			d--;
		}
		return d;
	}

	// check if a given year is a leap year
	static public boolean isLeapYear(int y) {
		if (y % 400 == 0)
			return true;
		else if (y % 100 == 0)
			return false;
		else if (y % 4 == 0)
			return true;
		else
			return false;
	}

	// check if y,m,d valid
	static public boolean valid(int y, int m, int d) {
		if (m < 1 || m > 12 || d < 1)
			return false;
		switch (m) {
			case 1:
			case 3:
			case 5:
			case 7:
			case 8:
			case 10:
			case 12:
				return d <= 31;
			case 4:
			case 6:
			case 9:
			case 11:
				return d <= 30;
			case 2:
				if (isLeapYear(y))
					return d <= 29;
				else
					return d <= 28;
		}
		return false;
	}

	// Return a string for the day like dd MMM yyyy
	public String toString() {

		final String[] MonthNames = {
				"Jan", "Feb", "Mar", "Apr",
				"May", "Jun", "Jul", "Aug",
				"Sep", "Oct", "Nov", "Dec" };

		return day + " " + MonthNames[month - 1] + " " + year;
	}

	// check if the current object is the end of a month
	public boolean isEndOfAMonth() {
		if (valid(year, month, day + 1)) // A smart methd: check whether (year month [day+1]) is still a valid date
			return false;
		else
			return true;
	}

	// create and return a new Day object which is the "next day" of the current day
	// object
	public Day next() {
		if (isEndOfAMonth())
			if (month == 12)
				return new Day(year + 1, 1, 1); // Since the current day is the end of the year, the next day should be
												// Jan 01
			else
				return new Day(year, month + 1, 1); // <== your task: first day of next month
		else
			return new Day(year, month, day + 1); // <== your task: next day of current month
	}

	// create and return a new Day object which is the "next day" of the current day
	// object
	public void advance() {

		if (isEndOfAMonth())
			if (month == 12) {
				year++;
				month = 1;
				day = 1; // Since the current day is the end of the year, the next day should be Jan 01
			} else {
				month++;
				day = 1;
			}
		else
			day++;
	}

}