public class PolyMorphDemo{
	public static void main(String[] args){
		Date date = new Date(2006,11,8);
		System.out.println(date);
		Date date2 = new Date(2006,12,31);
		System.out.println(date2);
		System.out.println(date.weeksLater(date2));
		System.out.println("the later date is " + Max.maxObj(date,date2));
	}
}
class Max{
	public static Comparable maxObj(Comparable o1, Comparable o2){
		if(o1.compareTo(o2)>= 0){
			return o1;
		}
		return o2;
	}
}
class Date implements Comparable{
	int year;
	int month;
	int day;
	public Date(){
		this((int) (2000*Math.random()) + 1000, (int)(12*Math.random()) + 1, (int)(31*Math.random()) + 1);
		
	}
	public Date(int yr, int mo, int da){
		year = yr;
		month = mo;
		day = da;
	}
	// advance the day by n
	public void advanceDay(){
		if (day < monthLength()) {
		    day = day + 1;
		}
		else {
			day = 1;
			month++;
		}
	}
	public String toString(){
		System.out.println("Date toString called");
		return "Year " + year + " Month " + month + " Day " + day;
	}
	public int monthLength(){
		if (month == 2)
			return 28;
		else if (month == 9 || month == 4 || month == 6 || month == 11)
			return 30;
		else
			return 31;
	}
	public boolean equals(Object other){
		System.out.println("Date equals called");
		if (other instanceof Date) {
		    Date otherDate = (Date)other;
		    return (this.year == otherDate.year &&
			    	this.month == otherDate.month &&
				    this.day == otherDate.day);
		}
		else{
		    return false;
		}
	}
	public boolean notEquals(Object other){
		return !equals(other);
	}
	public int compareTo(Object other){
		Date o = (Date) other;
		if(equals(o)){
			return 0;
		}
		if(year < o.year||year == o.year & month < o.month||
				year==o.year && month == o.month && day < o.day){
			return -1;
		}
		return 1;
	}
	public int weeksLater(Date other){
		int days = 0;
		if(this.compareTo(other) > 0){
			Date temp = new Date(other.year, other.month, other.day);
			while(!this.equals(temp)){
				temp.advanceDay();
				days++;
			}
			return days / 7;
		}
		else{
			Date temp = new Date(this.year, this.month, this.day);
			while(!other.equals(temp)){
				temp.advanceDay();
				days++;
			}
			return -days / 7;
		}
	}
}
class Time extends Date{
	private int hour;
	private int minute;
	private int second;
	public Time() {
		super();
		hour = (int) (24*Math.random());
		minute = (int) (60*Math.random());
		second = (int) (60*Math.random());
	}
	public Time(int yr, int mo, int da, int hr, int min, int sec){
		super(yr, mo, da);
		hour = hr;
		minute = min;
		second = sec;
	}
	public String toString(){
		return super.toString() + " Hour " + hour + " Minute " + minute + " Second " + second;
	}
	public boolean morning(){
		return (hour < 12);
	}
	public boolean equals(Object other){
		System.out.println("Time equals called");
		if (other instanceof Time) {
		    Time otherTime = (Time)other;
		    return super.equals(otherTime) &&
		           (this.hour == otherTime.hour &&
			    	this.minute == otherTime.minute &&
				    this.second == otherTime.second);
		}
		else{
		    return false;
		}
	}
	// this method is very confusing.  It does not do what
	// we intended it do when we wrote it in class.
	// You can ignore it, or if you are interested you
	// can try to see what is going on.
	public boolean equals(Object other1, Object other2){
		System.out.println("Time equals with 2 args called");
		// check if all 3 parameters are equal
		// better way: call the other equals twice
		// this is just for illustrating syntax
		if (other1 instanceof Time & other2 instanceof Time) {
		    Time otherTime1 = (Time)other1; //casts needed
		    Time otherTime2 = (Time)other2;
		    // idea of the following was so that Date equals 
		    // will be called - but is it?
		    Date date1 = otherTime1; //casts not needed
		    Date date2 = otherTime2;
		    return super.equals(otherTime1) &&
		           date1.equals(date2) &&
		           (this.hour == otherTime1.hour &&
			    	this.minute == otherTime1.minute &&
				    this.second == otherTime1.second &&
		            this.hour == otherTime2.hour &&
	    	        this.minute == otherTime2.minute &&
		            this.second == otherTime2.second);
		}
		else{
		    return false;
		}
	}
}