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

    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：