日付のソート

public class DateSort{
	public static void main(String[] args){
		Date[] days = new Date[5];
		days[0] = new Date(2001,5,1);
		days[1] = new Date(2001,4,1);
		days[2] = new Date(2002,10,1);
		days[3] = new Date(2002,1,15);
		days[4] = new Date(2008,8,8);

		System.out.println("    :");
		for(int i=0;i < days.length;i++){
			System.out.println(days[i]);
		}
		
		sort(days);
		System.out.println("     :");
		for(int i=0;i < days.length;i++){
			System.out.println(days[i]);
		}
	}
	
	public static Date[] sort(Date[] d){
		int len = d.length;
		for(int i=0;i<len;i++){
			for(int j = i+1;j<len;j++){
				if(d[i].compareTo(d[j]) > 0){
					Date temp = d[i];
					d[i] = d[j];
					d[j] = temp;
				}
			}
		}
		return d;
	}
}

class Date{
	int year,month,day;
	public Date(int year,int month,int day){
		this.year = year;
		this.month = month;
		this.day = day;
	}
	
	public int compareTo(Date antherDate){
		return year > antherDate.year?1
		:year < antherDate.year?-1
		:month > antherDate.month?1
		:month < antherDate.month?-1
		:day > antherDate.day?1
		:day<antherDate.day?-1:0;
	}
	public String toString(){
		return year+"/"+month+"/"+day;
	}
}