public class Day {

	private int yyyymmdd;

	// Constructor
	public Day(int y, int m, int d) {
		yyyymmdd = y * 10000 + m * 100 + d;
	}

	// Accessor methods
	public int getDay() {
		return yyyymmdd % 100;
	}

	public int getMonth() {
		return yyyymmdd % 10000 / 100;
	}

	public int getYear() {
		return yyyymmdd / 10000;
	}

	// 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 getDay() + " " + MonthNames[getMonth() - 1] + " " + getYear();
	}

	// 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;
	}

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

	// create and return a new Day object which is the "next day" of the current day
	// object
	public Day previous() {
		if (getDay() > 1)
			return new Day(getYear(), getMonth(), getDay() - 1);
		else if (getMonth() == 1)
			return new Day(getYear() - 1, 12, 31);
		else {
			return new Day(getYear(), getMonth() - 1, getMonthTotalDays(getYear(), getMonth() - 1));
		}
	}

}