Java-对象数组排序

1.对对象数组排序：对象要提供一个compare方法比较对象的大小

2.代码

 package Test;

 public class TestObjectArray {

     public static void main(String[] args) {
         Date [] dates = new Date[5];
         dates[0] = new Date(2000,1,2);
         dates[1] = new Date(2001,2,3);
         dates[2] = new Date(1997,9,8);
         dates[3] = new Date(2000,1,2);
         dates[4] = new Date(1997,9,3);

         for(Date d : dates){
             System.out.print(d+"\t");
         }

         System.out.println();
         bubbleSort(dates);

         for(Date d : dates){
             System.out.print(d+"\t");
         }

     }

     private static void bubbleSort(Date[] dates) {
         Date tmp;
         for(int i = dates.length - 1; i > 0; i--){
             for(int j = 0; j < i; j++){
                 if(dates[j].compare(dates[j+1]) > 0){
                     tmp = dates[j];
                     dates[j] = dates[j+1];
                     dates[j+1] = tmp;
                 }
             }
         }
     }

     //选择排序
     private static void selectSort(Date[] dates) {
         int index;
         Date temp;
         for(int i = 0; i < dates.length; i++){
             index = i;
             for(int j = i; j < dates.length; j++){
                 if(dates[index].compare(dates[j])>0){
                     index = j;
                 }
             }
             if(i!=index){
                 temp = dates[i];
                 dates[i] = dates[index];
                 dates[index] = temp;
             }
         }
     }

 }

 class Date{
     int year, month, day;

     public int getMonth() {
         return month;
     }

     public int getDay() {
         return day;
     }

     public int getYear() {
         return year;
     }

     public Date(int year, int month, int day) {
         super();
         this.year = year;
         this.month = month;
         this.day = day;
     }

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

     public int compare(Date d){
         return     this.getYear() > d.getYear() ? 1 :
                 this.getYear() < d.getYear() ? -1 :    //年份即不是大于，又不是小于，则一定是等于，等于则继续比较月份
                 this.getMonth() > d.getMonth() ? 1 :
                 this.getMonth() < d.getMonth() ? -1:
                 this.getDay() > d.getDay() ?  1 :
                 this.getDay() < d.getDay() ? -1 : 0;
     }
 }

3.运行结果：