java 날짜계산

출처: https://sowon-dev.github.io/2021/07/14/210715Calendar/

String으로 날짜 가지고 놀기

private String[][] setDateAtColumns(String[][] columnsWeek, String strFromDate) {
        SimpleDateFormat formatYMD = new SimpleDateFormat("yyyy-MM-dd");

        try {
                Date fromDate = formatYMD.parse(strFromDate);
                Calendar cal = Calendar.getInstance();
                cal.setTime(fromDate);
                for(int i=2; i<16; i++) {
                        columnsWeek[i][0] = formatYMD.format(cal.getTime()) +                 columnsWeek[i][0];
                        i++;
                        columnsWeek[i][0] = formatYMD.format(cal.getTime()) + columnsWeek[i][0];
                        cal.add(Calendar.DATE, 1);
                }
        } catch (Exception e) {
                throw new GlobalException("엑셀 날짜계산 오류", true);
        }

        return columnsWeek;
}