code: public static long getDateQuot(String time1, String time2) {
          long quot = 0;
          SimpleDateFormat ft = new SimpleDateFormat("yyyy-MM-dd");
          try {
              Date date1 = ft.parse(time1);
              Date date2 = ft.parse(time2);
              quot = date2.getTime() - date1.getTime();
              quot = quot / 1000 / 60 / 60 / 24;
          } catch (ParseException e) {
              e.printStackTrace();
          }
          return quot;
      }
docs: 两个日期之间的天数
  
  @param time1
  @param time2
  @return