Java programming time and date API instance analysis

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/**
  * Date tool class
  * @author yanweiqi
  * @since 2016-5-6
  *
  */
public class LocalDateUtils {
	private static ZoneId zone = ();
	/**
    * String to Date
    * @param date
    * @return
    * @throws Exception
    */
	public static Date convertToDate(String date) throws Exception{
		LocalDate localDate = null;
		if(null == date){
			throw new NullPointerException("date isn't null");
		} else {
			localDate = (date);
			return convertToDate(localDate);
		}
	}
	/**
    * String to LocalDateTime
    * @param date
    * @return localDateTime
    */
	public static LocalDateTime convertToLocalDateTime(String date){
		LocalDateTime localDateTime = null;
		if(null == date){
			throw new NullPointerException("date isn't null");
		} else {
			localDateTime = (date);
			return localDateTime;
		}
	}
	/**
    * LocalDate to Date
    * @param localDate
    * @return Date
    */
	public static Date convertToDate(LocalDate localDate){
		Instant instant = ().atZone(zone).toInstant();
		return (instant);
	}
	/**
    * LocalDate to Date
    * @param localDateTime
    * @return Date
    */
	public static Date convertToDate(LocalDateTime localDateTime){
		Instant instant = (zone).toInstant();
		return (instant);
	}
	/**
    * Date to LocalDate
    * @param date
    * @return localDate
    */
	public static LocalDate convertToLocalDate(Date date){
		Instant instant = ();
		return convertToLocalDateTime(instant).toLocalDate();
	}
	/**
    * Date to LocalTime
    * @param date
    * @return localDate
    */
	public static LocalTime convertToLocalTime(Date date){
		Instant instant = ();
		return convertToLocalDateTime(instant).toLocalTime();
	}
	/**
    * Date to LocalDatetime
    * @param date
    * @return localDate
    */
	public static LocalDateTime convertToLocalDateTime(Date date){
		Instant instant = ();
		return convertToLocalDateTime(instant);
	}
	/**
    * Instant to LocalDateTime
    * @param instant
    * @return
    */
	public static LocalDateTime convertToLocalDateTime(Instant instant){
		return (instant, zone);
	}
	/**
    * LocalDateTime to Instant
    * @param localDateTime
    * @return
    */
	public static Instant convertToInstant(LocalDateTime localDateTime){
		return (zone).toInstant();
	}
	/**
    * LocalDate to Instant
    * @param localDate
    * @return
    */
	public static Instant convertToInstant(LocalDate localDate){
		return (zone).toInstant();
	}
	/**
    * LocalDate to LocalDateTime
    * @param localDate
    * @return LocalDateTime
    */
	public static LocalDateTime convertToLocalDateTime(LocalDate localDate){
		return ();
	}
	/**
    *Daily cycle formatting
    * @param localDateTime
    * @param formatStyle
    * @return
    */
	public static String formatter(LocalDateTime localDateTime, String formatStyle){
		return (formatStyle).format(localDateTime);
	}
	/**
    * Set year
    * @param sourceDate
    * @param year
    * @return LocalDateTime
    */
	public static LocalDateTime setYear(LocalDateTime sourceDate, Integer year){
		return (year);
	}
	/**
    * Set the month
    * @param sourceDate
    * @param month
    * @return LocalDateTime
    */
	public static LocalDateTime setMonth(LocalDateTime sourceDate, Integer month){
		return (month);
	}
	/**
    * Set the day
    * @param sourceDate
    * @param month
    * @return LocalDateTime
    */
	public static LocalDateTime setDayOfMonth(LocalDateTime sourceDate, Integer dayOfMonth){
		return (dayOfMonth);
	}
	/**
    * Set hours
    * @param sourceDate
    * @param hour
    * @return
    */
	public static LocalDateTime setHour(LocalDateTime sourceDate,Integer hour){
		return (hour);
	}
	/**
    * Set minutes
    * @param sourceDate
    * @param minute
    * @return
    */
	public static LocalDateTime setMinute(LocalDateTime sourceDate,Integer minute){
		return (minute);
	}
	/**
    * Set seconds
    * @param sourceDate
    * @param second
    * @return
    */
	public static LocalDateTime setSecond(LocalDateTime sourceDate,Integer second){
		return (second);
	}
	/**
    * Modify the year, month, date
    * @param sourceDate
    * @param year
    * @param month
    * @param dayOfMonth
    * @return
    */
	public static LocalDateTime setYMD(LocalDateTime sourceDate, Integer year, Integer month, Integer dayOfMonth) {
		return (year).withMonth(month).withDayOfMonth(dayOfMonth);
	}
	/**
    * Modify time, minute and second
    * @param sourceDate
    * @param hour
    * @param minute
    * @param second
    * @return
    */
	public static LocalDateTime setHMS(LocalDateTime sourceDate,Integer hour, Integer minute, Integer second) {
		return (hour).withMinute(minute).withSecond(second);
	}
	/**
    * Calculate the number of days of difference
    * @param beginDate
    * @param endDate
    * @return
    */
	public static int getInteverDays(LocalDate beginDate,LocalDate endDate){
		Period period = (beginDate, endDate);
		return ();
	}
	/**
    * Date addition and subtraction
    * @param num quantity
    * @param unit
    * @param LocalDate Original date
    * @return LocalDate The date after the increase
    */
	@SuppressWarnings("static-access")
	  public static LocalDate addLocalDate(long num,ChronoUnit unit,final LocalDate localDate){
		LocalDate resultDate;
		if(num > 0){
			resultDate = ().plus(num, unit);
		} else {
			resultDate = ().minus((num), unit);
		}
		return resultDate;
	}
	/**
    * Date, hour, minute and second
    * @param num quantity
    * @param unit
    * @param localDateTime Original date
    * @return LocalDateTime The date after the increase
    */
	@SuppressWarnings("static-access")
	  public static LocalDateTime addLocalDateTime(long num,ChronoUnit unit,LocalDateTime localDateTime){
		LocalDateTime resultDateTime;
		if(num > 0){
			resultDateTime = ().plus(num, unit);
		} else {
			resultDateTime = ().minus((num),unit);
		}
		return resultDateTime;
	}
	/**
    * Add or subtract from hours, minutes and seconds
    * @param num quantity
    * @param unit
    * @param localTime Original date
    * @return LocalDateTime The date after the increase
    */
	@SuppressWarnings("static-access")
	  public static LocalTime addLocalTime(long num,ChronoUnit unit,LocalTime localTime){
		LocalTime resultTime;
		if(num > 0){
			resultTime = ().plus(num, unit);
		} else {
			resultTime = ().minus((num), unit);
		}
		return resultTime;
	}
	public static void main(String[] args){
		LocalDateTime time = ();
		String rr = formatter(time, "yyyy-MM-dd HH:mm:ss");
		(rr);
		LocalDateTime time2 = addLocalDateTime(-2, , time);
		String yy = formatter(time2, "yyyy-MM-dd HH:mm:ss");
		(yy);
	}