code: public static String prettyDateTime(String time) {
          if (time.length() < 12) return time;
          StringBuilder sb = new StringBuilder();
          sb.append(time.substring(0, 4)).append("-").append(time.substring(4, 6)).append("-").append(time.substring(6, 8));
          sb.append(" ").append(time.substring(8, 10)).append(":").append(time.substring(10, 12));
          return sb.toString();
      }
docs: change 20150812161819 to 2015-08-12 16:18