Java日期推迟计算、日期大小

  /**
      * 日期推迟计算
      * @param date
      * @param num
      * @return java.util.HashMap<java.lang.String,java.lang.String>
      */
     public static String dateAdd(String date, int num) throws ParseException {
         SimpleDateFormat sj = new SimpleDateFormat("yyyy-MM-dd");
         Date dateFormat = sj.parse(date);
         Calendar calendar = Calendar.getInstance();
         calendar.setTime(dateFormat);
         calendar.add(calendar.DATE, num);
         //System.out.println("期望日期：" + sj.format(calendar.getTime()));
         return sj.format(calendar.getTime());
     }

  /**
      * 是否超过指定日期
      *
      * @param
      * @return
      */
     public boolean dateJudge(String start, String end) throws ParseException {
         SimpleDateFormat sj = new SimpleDateFormat("yyyy-MM-dd");
         Date startDate = sj.parse(start);
         Date endDate = sj.parse(end);
         if (startDate.before(endDate)) {
             return false;
         } else {
             return true;
         }
     }

  public static void main(String[] args) throws ParseException {
         String startDate = "2015-01-01";
         String endDate = "2015-01-15";
         String newDate = dateAdd(startDate, 1);

         while (dateJudge(newDate, endDate)) {
             String tempStartDate = dateAdd(newDate, -1);
             System.out.println(tempStartDate + "___" + newDate);
             newDate = dateAdd(newDate, 1);
         }

     }

 public static void main(String[] args) throws ParseException {
         String startDate = "2015-01-01";
         String endDate = "2015-01-17";
         String newDate = startDate;

         while (dateJudge(newDate, endDate)) {
             if (dateJudge(dateAdd(newDate, 2), endDate)) {
                 System.out.println(newDate.concat(" 00:00:00__________") + dateAdd(newDate, 2).concat(" 23:59:59"));
                 newDate = dateAdd(newDate, 3);
             } else {
                 break;

             }
         }
         while (dateJudge(newDate, endDate)) {
             System.out.println(newDate);
             newDate = dateAdd(newDate, 1);
         }
     }