Java获取多少秒钟之后的时间

Calendar calendar = Calendar.getInstance();
calendar.add(Calendar.SECOND, 7200);   //2小时之后的时间
 SimpleDateFormat sdf = new SimpleDateFormat("yyyy-M-dd HH:mm:ss");
  String token_yxq = sdf.format(calendar.getTime());
 System.out.println(token_yxq);