Easy Date Util Class for Age calculations (Joda Time dependant)

gistfile1.txt

package br.com.andreluisdias.examples.date;

import org.joda.time.Days;
import org.joda.time.LocalDate;

import java.util.Calendar;
import java.util.Date;

/**
 * DATE UTIL CLASS.
 * 
 * @author Andre Luis de Oliveira Dias
 * @date 28/01/2014
 */
public final class DateUtil {
	
	/**
	 * @return
	 */
	public static Date getSystemDate() {
		
		return Calendar.getInstance().getTime();
	}
	
	/**
	 * Calculate the age, please.
	 * 
	 * @param birthDate
	 * 		Birth Date
	 * 
	 * @return
	 * 		Age
	 */
	public static int calculateAge(Date birthDate) {

		Calendar sysdate = Calendar.getInstance();
		Calendar birth = Calendar.getInstance();
		birth.setTime(birthDate);

		int diffDay = sysdate.get(Calendar.DAY_OF_MONTH) - birth.get(Calendar.DAY_OF_MONTH);
		int diffMonth = sysdate.get(Calendar.MONTH) - birth.get(Calendar.MONTH);
		
		int result = (sysdate.get(Calendar.YEAR) - birth.get(Calendar.YEAR)) - 1;
		if (diffMonth >= 0 && diffDay >= 0 ) {
			result++;
		}
		
		return (result < 0) ? 0 : result;
	}
	
	/**
	 * Calculate the days between the start and the end date.
	 * 
	 * @param startDate
	 * 		Start date
	 * 
	 * @param endDate
	 * 		Finish date
	 * 
	 * @return
	 * 		Days between the start and the end date.
	 */
	public static int daysBetween(Date startDate, Date endDate) {

		return Days.daysBetween(
				new LocalDate(startDate), new LocalDate(endDate)).getDays(); 
	}
}

If you'd like to test it, create a 'main' method, with a simple static call:

DateUtil.calculateAge(someDate);