java 解决时间相减问题

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;


public class MainActivity {

    /*public static void main(String[] args) {
        // TODO Auto-generated method stub
        int[] A = { 1,8,2,5,4,3,6 };
        int[] B = Insertion.sort(A);
        print(B);
        
    }
    
    static void print(int[] arr) {
        for(int i=0; i<arr.length; i++) {
            System.out.print(arr[i]+" ");
        }
    }*/
    
    public static void main(String[] args) throws Exception{
         /* Date date1 = new SimpleDateFormat("yyyy-MM-dd").parse("2015-04-24 12:14:57"); 
          Date date2 = new SimpleDateFormat("yyyy-MM-dd").parse("2015-03-25 12:14:57");
          Calendar cal1=Calendar.getInstance();
          Calendar cal2=Calendar.getInstance();
          cal1.setTime(date1);
          cal2.setTime(date2);
          
          System.out.println(date1.compareTo(date2));
          System.out.println(cal1.compareTo(cal2));
          String now = new SimpleDateFormat("yyyy年MM月dd日").format(date1);
          System.out.println(now);*/
        
           SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
           java.util.Date now = df.parse("2015-04-24 12:14:57");
           java.util.Date date=df.parse("2015-03-25 12:14:57");
           long l=now.getTime()-date.getTime();
           long day=l/(24*60*60*1000);
           long hour=(l/(60*60*1000)-day*24);
           long min=((l/(60*1000))-day*24*60-hour*60);
           long s=(l/1000-day*24*60*60-hour*60*60-min*60);
           System.out.println(""+day+"天"+hour+"小时"+min+"分"+s+"秒");
         }
    
    

}