list数组排序 Collections 按Date时间降序排列

    @ResponseBody
    @RequestMapping(value = {"K12", "12"})
    public String refurbishLights(KdDynamic kdDynamic, HttpServletRequest request, HttpServletResponse response, Model model) {
        List<KdDynamic> kdDynamics=kdDynamicService.findList(kdDynamic);
        Collections.sort(kdDynamics, new Comparator<KdDynamic>(){
            /*
             * int compare(KdDynamic kd1, KdDynamic kd2) 返回一个基本类型的整型，
             * 返回负数表示：kd2 小于kd1，
             * 返回0 表示：kd1和kd2相等，
             * 返回正数表示：kd2大于kd1
             */
            public int compare(KdDynamic kd1, KdDynamic kd2) {
                //按照kd1的更新时间进行降序排列
                if(kd2.getDtime().before(kd1.getDtime())){
                    return -1;
                }
                if(kd1.getDtime() == kd1.getDtime()){
                	return 0;
                }
                return 1;
            }

        });
		String jsonStr = null;
		JSONArray array = new JSONArray();
		/* Json格式的数组形式 */
		JSONObject obj;
		/* json格式的单个对象形式 */
		for (int i = 0; i < kdDynamics.size(); i++ )
		{
		    obj = new JSONObject();
		    obj.put( "dnum", kdDynamics.get(i).getDnum() );
		    obj.put( "dtime", df.format(kdDynamics.get(i).getDtime() ));
		    /* json通过put方式以key-value形式填充 */
		    obj.put( "dcontext", kdDynamics.get(i).getDcontext() );
		    array.put(obj);
		    /* 将JSONObject添加入JSONArray */
		}
		model.addAttribute("index", "ddzt");
		model.addAttribute( "kdDynamics", kdDynamics );
		model.addAttribute( "kdDynamicsJSON", array.toString());
		System.out.println("====================================");
		System.out.println(array.toString());
		System.out.println("====================================");
		return array.toString();
    }