DateUtil

public class DateUtil {

    private static final ZoneId ZONE_ID = ZoneId.systemDefault();
    private static final DateTimeFormatter DATETIME = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
    private static final DateTimeFormatter DATE = DateTimeFormatter.ofPattern("yyyy-MM-dd");
    private static final DateTimeFormatter SHORT_DATE = DateTimeFormatter.ofPattern("yyyyMMdd");

    public static String toDatetimeString(Date date){
        return date != null ? DATETIME.format(date.toInstant().atZone(ZONE_ID).toLocalDateTime()) : null;
    }

    public static String toDateString(Date date){
        return date != null ? DATE.format(date.toInstant().atZone(ZONE_ID).toLocalDate()) : null;
    }

    public static String toShortDateString(Date date){
        return date != null ? SHORT_DATE.format(date.toInstant().atZone(ZONE_ID).toLocalDate()) : null;
    }

    public static Date parseDatetime(String string) {
        return string != null && !string.isEmpty() ? Date.from(LocalDateTime.parse(string, DATETIME).atZone(ZONE_ID)
            .toInstant()) : null;
    }

    public static Date parseDate(String string) {
        return string != null && !string.isEmpty() ? Date.from(LocalDate.parse(string, DATE).atStartOfDay()
            .atZone(ZONE_ID).toInstant()) : null;
    }

    public static String dateAdd(int date) {
        return DATETIME.format(LocalDate.now().plusDays(date).atStartOfDay());
    }

    public static String datetimeAdd(int date) {
        return DATETIME.format(LocalDateTime.now().plusDays(date));
    }

    public static String datetimeAdd(String string, int date) {
        return string != null && !string.isEmpty() ? DATETIME.format(LocalDateTime.parse(string, DATETIME).plusDays(date))
            : null;
    }
}