xml date conversion all date conversions

public static String convertXMLGregorianCalendarToString( XMLGregorianCalendar xmlGregorianCalendar ) {
	return convertDateToString( convertXMLGregorianCalendarToUtilDate( xmlGregorianCalendar ), DATE_FORMAT_YYYY_MM_DD );
    }

public static XMLGregorianCalendar convertStringToXMLGregorianCalendar( String strDate ) throws ParseException, DatatypeConfigurationException {
	return convertDateToXMLGregorianCalendar( convertStringToDate( strDate, DATE_FORMAT_YYYY_MM_DD ) );
    }

public static Date convertXMLGregorianCalendarToUtilDate(XMLGregorianCalendar xmlGregorianCalendar){
		
		Date carDate =  new java.util.Date();
		if(xmlGregorianCalendar!=null){
			XMLGregorianCalendar calendar = xmlGregorianCalendar;
			carDate = new Date(calendar.toGregorianCalendar().getTimeInMillis());
		}
		return carDate;
	}
	
	public static Date convertStringToDate(String inputDate) {
		
		SimpleDateFormat dateFormat = new SimpleDateFormat("EEE MMM dd HH:mm:ss z yyyy");
		Date date = new Date();
		try {
			date = dateFormat.parse(inputDate);
			dateFormat.format(date);
		} catch (ParseException e) {
			
		}	
		return date;	
	}
	
	public static Date convertNonFormattedDateStringToUtilDate(String inputDate,String dateFormatType) {
		
		SimpleDateFormat dateFormat = new SimpleDateFormat(dateFormatType);
		Date date = new Date();
		try {
			date = dateFormat.parse(inputDate);
			dateFormat.format(date);
		} catch (ParseException e) {
			
		}	
		return date;	
	}
	
	/**
	 * Converts a the Date to a string in the following format : yyyy/MM/dd 
	 * @param inputeDate
	 * @return String - date in the following format: yyyy/MM/dd
	 */
	public static String convertDateToString(Date inputeDate, String dateFormat){
		if (inputeDate == null){
			inputeDate = new Date();
		}
		//String DATE_FORMAT = "yyyy/MM/dd";
	    SimpleDateFormat sdf = new SimpleDateFormat(dateFormat);
	    return sdf.format(inputeDate);
	}

public static Date convertStringToDate(String inputDate, String pattern) throws ParseException{
		
		SimpleDateFormat dateFormat = new SimpleDateFormat(pattern);
		Date date = null;
		// Following method call is not thread-safe,
        // so synchronizing it
		synchronized( dateFormat ) {
			date = dateFormat.parse(inputDate);
		}
		return date;	
	}
    
    public static String formatDateToString(Date date, String pattern){
    	SimpleDateFormat dateFormat = new SimpleDateFormat(pattern);
    	String dateString = dateFormat.format(date);
    	return dateString;
    }
    
    public static XMLGregorianCalendar convertCalenderToXMLGregorianCalendar(Calendar date)
	throws DatatypeConfigurationException{
		if (date != null){
			XMLGregorianCalendar gregCreationDate = DatatypeFactory.newInstance().newXMLGregorianCalendar();
	    	gregCreationDate.setYear(date.get(Calendar.YEAR));
	    	gregCreationDate.setDay(date.get(Calendar.DAY_OF_MONTH));
	    	gregCreationDate.setMonth(date.get(Calendar.MONTH)+ 1);
	    	gregCreationDate.setHour(date.get(Calendar.HOUR_OF_DAY));
	    	gregCreationDate.setMinute(date.get(Calendar.MINUTE));
	    	gregCreationDate.setSecond(date.get(Calendar.SECOND));
	    	gregCreationDate.setMillisecond(date.get(Calendar.MILLISECOND));
	    	// Calendar ZONE_OFFSET and DST_OFFSET fields are in milliseconds.
	    	int offsetInMinutes = (date.get(Calendar.ZONE_OFFSET) + date.get(Calendar.DST_OFFSET)) / (60 * 1000);
	    	gregCreationDate.setTimezone(offsetInMinutes); 
	    	return gregCreationDate;
		}
	return null;
    }
    
    public static XMLGregorianCalendar convertDateToXMLGregorianCalendar(Date date)
	throws DatatypeConfigurationException {
	if (date != null){
	   	Calendar cal = Calendar.getInstance();
		cal.setTime( date );
		XMLGregorianCalendar gregCreationDate = DatatypeFactory.newInstance().newXMLGregorianCalendar();
    	gregCreationDate.setYear(cal.get(Calendar.YEAR));
    	gregCreationDate.setDay(cal.get(Calendar.DAY_OF_MONTH));
    	gregCreationDate.setMonth(cal.get(Calendar.MONTH)+ 1);
    	gregCreationDate.setHour(cal.get(Calendar.HOUR_OF_DAY));
    	gregCreationDate.setMinute(cal.get(Calendar.MINUTE));
    	gregCreationDate.setSecond(cal.get(Calendar.SECOND));
    	gregCreationDate.setMillisecond(cal.get(Calendar.MILLISECOND));
    	// Calendar ZONE_OFFSET and DST_OFFSET fields are in milliseconds.
    	int offsetInMinutes = (cal.get(Calendar.ZONE_OFFSET) + cal.get(Calendar.DST_OFFSET)) / (60 * 1000);
    	gregCreationDate.setTimezone(offsetInMinutes); 
    	return gregCreationDate;
	}
    return null;
    }

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I am wondering how can I refine thiese methods