关于list的排序

public static void listSortByTime(List<HashMap<String, String>> list) {
  Collections.sort(list, new CollatorComparator());
 }

 public static class CollatorComparator implements Comparator {
  public int compare(Object element1, Object element2) {
   HashMap<String, String> map1 = (HashMap<String, String>)element1;
   HashMap<String, String> map2 = (HashMap<String, String>)element2;
   SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
   Date date1;
   try {
    date1 = sdf.parse(map1.get("sortTime"));
    Date date2 = sdf.parse(map2.get("sortTime"));
    if(date1.after(date2)) return 1;
    return -1;
   } catch (ParseException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
    return 0;
   }
   
  }
 }