[JAVA] 시작일과 종료일 사이의 날짜 가져오기

    /**
     * beginDate 부터 endDate 사이의 날짜 가져오기
     *
     * ex) beginDate == 20200930, endDate == 20201004 일 때,
     *     [20200930, 20201001, 20201002, 20201003, 20201004] 리턴
     * @param beginDate
     * @param endDate
     * @return
     * @throws Exception
     */
    private ArrayList<String> getDaysBetweenDates(String beginDate, String endDate) throws Exception {
        if (beginDate != null && beginDate.length() >= 8) {
            beginDate = beginDate.substring(0, 8);
        } else {
            return null;
        }
       
        if (endDate != null && endDate.length() >= 8) {
            endDate = endDate.substring(0, 8);
        } else {
            return null;
        }
       
        int iBeginDate = Integer.parseInt(beginDate);
        int iEndDate = Integer.parseInt(endDate);
        if (iBeginDate > iEndDate) {
            return null;
        }
       
       
        // 시작날짜 세팅
        int beginYear = Integer.parseInt(beginDate.substring(0, 4));
        int beginMonth = Integer.parseInt(beginDate.substring(4, 6));
        int beginDay = Integer.parseInt(beginDate.substring(6, 8));
       
        Calendar cal = Calendar.getInstance();
        cal.set(beginYear, beginMonth – 1, beginDay);
       
       
        ArrayList<String> resultList = new ArrayList<String>();
       
        SimpleDateFormat sdf = new SimpleDateFormat(“yyyyMMdd”);
        String oneDay = “”;
       
        // beginDate 부터 endDate 사이의 날짜 담기
        while (Integer.parseInt(sdf.format(cal.getTime())) <= iEndDate) {
            oneDay = sdf.format(cal.getTime());
            resultList.add(oneDay);
           
            // 다음날로 날짜 조정
            cal.add(Calendar.DATE, 1);
        }
       
        return resultList;
    }