[Java ]DateUtils

package com.urmoments.api.utils;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.Locale;

/**
 * This class contains methods concerning the Date. It contains a method which 
 * calculates the age of a people from his birth date.
 *
 */
public class DateUtils {

	private static SimpleDateFormat fullFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ");
	private static SimpleDateFormat nameOfDayFormat = new SimpleDateFormat("EEEE", Locale.ENGLISH);
	private static SimpleDateFormat timeFormat = new SimpleDateFormat("HH:mm");
	
	/**
	 * This static methods calculate the age of a person from 
	 * his birth date.
	 * 
	 * @param birthDate Date object representing the Date of a person
	 * 
	 * @return the age of the person, as a int
	 */
	public static int calculateAgeFromDate(Date birthDate){
		int age = 0;
		
		return age;
	}
	
	
	
	/**
	 * This method converts a Date object to a String as in this example:
	 * "Friday 6th at 16:39".
	 * 
	 * @param date the Date object to convert
	 * 
	 * @return the converted date as a String
	 */
	public static String convertDateToStringDayAndHour(Date date){
		String ret = null;
		
		// construct the Calendar instance
		Calendar cal = Calendar.getInstance();
		cal.setTime(date);
		
		// construct the parts of the final String
		String dayOfWeek = nameOfDayFormat.format(date);
		String dayOfMonth = Integer.toString(cal.get(Calendar.DAY_OF_MONTH));
		String time= timeFormat.format(date);

		String daySuffix = "";
		switch (cal.get(Calendar.DAY_OF_MONTH)) {
		case 1:
			daySuffix = "st";
			break;
		case 2:
			daySuffix = "nd";
			break;
		case 3:
			daySuffix = "rd";
			break;
		default:
			daySuffix = "th";
			break;
		}
		
		ret = dayOfWeek + " " + dayOfMonth + daySuffix + " at " + time;
		
		return ret;
	}
	
	
	
	
	/**
	 * This method converts a Date object to a String in the correct format.
	 * 
	 * @param date the Date object to convert
	 * 
	 * @return the converted date as a String
	 */
	public static String convertDateToStringFull(Date date){
		String dateStr = null;
		
		dateStr = fullFormat.format(date);
		
		return dateStr;
	}
	
	
	/**
	 * This method converts a String to a Date.
	 * 
	 * @param dateStr the date to convert
	 * 
	 * @return the converted Date
	 * 
	 * @throws ParseException 
	 */
	public static Date convertStringToDateFull(String dateStr) throws ParseException{
		Date date = null;
		
		date = fullFormat.parse(dateStr);
		
		return date;
	}
	
}