java例程练习（对象类型数据的排序）

public class TestSort {
	public static void main(String[] args) {
		Date[] days =  new Date[5];
		days[0] = new Date(2004, 8, 6);
		days[1] = new Date(2007, 4, 6);
		days[2] = new Date(2007, 4, 9);
		days[3] = new Date(2004, 4, 6);
		days[4] = new Date(2004, 4, 5);
		
		bubbleSort(days);
		
		for(int i = 0; i < days.length; i++) {
			System.out.println(days[i]);
		}
	}
	
	public static Date[] bubbleSort(Date[] a) {
		int len = a.length;
		for(int i = len - 1; i >= 1; i--) {
			for(int j = 0; j <= i -1; j++) {
				if(a[j].compare(a[j + 1]) > 0) {
					Date temp = a[j];
					a[j] = a[j + 1];
					a[j + 1] = temp;
				}
			}
		}
		return a;
	}
}

class Date {
	int year;
	int month;
	int day;
	
	Date(int y, int m, int d) {
		year = y;
		month = m;
		day = d;
	}
	
	public int compare(Date date) {
		return year > date.year ? 1
				: year < date.year ? -1
				:month > date.month ? 1
				:month > date.month ? -1
				:day > date.day ? 1
				:day < date.day ? -1 
				: 0;
	}

	public String toString() {
		return "" + year + "-" + month + "-" + day;
	}
}