public class DateDemo {
	public static void main(String[] args) {
		System.out.println("number of months in a year == "
			+ MyDate.numberOfMonths());
		System.out.println();

		MyDate d = new MyDate(1, 29, 2020);
		System.out.println(d);  //means System.out.println(d.toString());

		d.next();
		System.out.println(d);

		d.next(10);
		System.out.println(d);

		System.exit(0);
	}
}

class MyDate {
	private static final int[] length = {
		0,	//so January will have subscript 1
		31,	//January
		28,	//February: ignoring leap years for the time being
		31,	//March
		30,	//April
		31,	//May
		30,	//June
		31,	//July
		31,	//August
		30,	//September
		31,	//October
		30,	//November
		31	//December
	};

	private int year;
	private int month;	//1 to 12 inclusive
	private int day;

	public MyDate(int month, int day, int year) {	//constructor
		if (year == 0) {
			System.err.println("There was no Year Zero.");
			System.exit(1);   //should've thrown an exception
		}
		this.year = year;

		if (month < 1 || month > 12) { //or month >= length.length
			System.err.println("bad month " + month);
			System.exit(1);
		}
		this.month = month;

		if (day < 1 || day > length[month]) {
			System.err.println("bad day " + day);
			System.exit(1);
		}
		this.day = day;
	}

	public String toString() {
		return month + "/" + day + "/" + year;
		//Could also say
		//return this.month + "/" + this.day + "/" + this.year;
	}

	public void next() {
		if (++day > length[month]) {
			day = 1;
			if (++month > 12) {
				month = 1;
				if (year == Integer.MAX_VALUE) {
					System.err.println("already in year "
						+ year);
					System.exit(1);
				}
				++year;
			}
		}
	}

	public void next(int i) {
		for (; i > 0; --i) {
			next();		//One method can call another method.
		}
	}

	//Return the Julian date of this date (1 to 365 inclusive).
	//For example, the Julian date of April 16 is 31 + 28 + 31 + 16 == 106.

	public int julian() {
		//You will write the body of this method
		//in place of the following dummy statement.
		return 0;
	}

	/*
	Like the compareTo method in BubbleSortStrings.java.
	Return 0 if this MyDate is the same date as the other.
	Return a negative int if this MyDate is earlier than the other.
	Return a positive int if this MyDate is later than the other.
	*/

	public int compareTo(MyDate other) {
		/*
		You will write the body of this method
		in place of the following dummy statement.
		The fields of this date are year, month, day.
		For clarity, you can also call then this.year, this.month, this.day
		The fields of the other date are other.year, other.month, other.day
		*/
		return 0;
	}

	public static int numberOfMonths() {
		return length.length - 1;
	}

	public static int numberOfDays() {
		/*
		You will write the body of this method
		in place of the following dummy statement.
		It should return 365, the number of days in a year.
		*/
		return 0;
	}
}