Java Age Calculate age(Date birthdate, Date asOf)

Description

Compute the age returning an array of integers, for year, month, and day respectively.

License

Open Source License

Parameter

Parameter	Description
birthdate	The start date to start the age computation.
asOf	The end date for the age computation

Return

The age in years, months, days in the 0, 1, 2 indices respectively.

Declaration

public static int[] age(Date birthdate, Date asOf) 

Method Source Code

//package com.java2s;
/*//w w  w .j  ava 2s . c o  m
 * CONFIDENTIAL AND PROPRIETARY SOURCE CODE OF
 * Institute of Systems Science, National University of Singapore
 *
 * Copyright 2012 Team 4(Part-Time), ISS, NUS, Singapore. All rights reserved.
 * Use of this source code is subjected to the terms of the applicable license
 * agreement.
 *
 * -----------------------------------------------------------------
 * REVISION HISTORY
 * -----------------------------------------------------------------
 * DATE             AUTHOR          REVISION      DESCRIPTION
 * 10 March 2012    Chen Changfeng   0.1            Class creating
 *                                        
 *                                        
 *                                        
 *                                        
 * 
 */

import java.util.*;

public class Main {
    /**
     * Compute the age returning an array of integers, for year, month, and day respectively.
     * <p>
     * @param  birthdate The start date to start the age computation.
     * @param  asOf      The end date for the age computation
     * @return The age in years, months, days in the 0, 1, 2 indices respectively.
     */
    public static int[] age(Date birthdate, Date asOf) {
        Calendar from = Calendar.getInstance();
        Calendar to = Calendar.getInstance();
        from.setTime(birthdate);
        to.setTime(asOf);

        int birthYYYY = from.get(Calendar.YEAR);
        int birthMM = from.get(Calendar.MONTH);
        int birthDD = from.get(Calendar.DAY_OF_MONTH);

        int asofYYYY = to.get(Calendar.YEAR);
        int asofMM = to.get(Calendar.MONTH);
        int asofDD = to.get(Calendar.DAY_OF_MONTH);

        int ageInYears = asofYYYY - birthYYYY;
        int ageInMonths = asofMM - birthMM;
        int ageInDays = asofDD - birthDD;

        if (ageInDays < 0) {
            // Guaranteed after this single treatment, ageInDays will be >= 0.
            // i.e. ageInDays = asofDD - birthDD + daysInBirthMM.
            ageInDays += from.getActualMaximum(Calendar.DAY_OF_MONTH);
            ageInMonths--;
        }

        if (ageInDays == to.getActualMaximum(Calendar.DAY_OF_MONTH)) {
            ageInDays = 0;
            ageInMonths++;
        }

        if (ageInMonths < 0) {
            ageInMonths += 12;
            ageInYears--;
        }
        if (birthYYYY < 0 && asofYYYY > 0)
            ageInYears--;

        if (ageInYears < 0) {
            ageInYears = 0;
            ageInMonths = 0;
            ageInDays = 0;
        }

        int[] result = new int[3];
        result[0] = ageInYears;
        result[1] = ageInMonths;
        result[2] = ageInDays;
        return result;
    }

    /**
     * Retrieves the value of the field in the Date.
     * Some common fields that is likely to be used include :
     * <p>
     * <li>Calendar.YEAR - retrieves the year value
     * <li>Calendar.MONTH - retrieves the month value ( 1 - 12 )
     * <li>Calendar.DAY_OF_MONTH - retrieve the day value ( 1 - 31 )
     * <li>Calendar.HOUR - retrieves the hours value in 12 hour format ( 1 - 12 )
     * <li>Calendar.HOUR_OF_DAY - retrieves the hours value in 24 hour format ( 0 - 23 )
     * <li>Calendar.MINUTE - retrieves the minutes value ( 0 - 59 )
     * <li>Calendar.AM_PM - retrieves the am/pm value ( 0 = am; 1 = pm )
     * <p>
     * @param  date  The Date object to extract value from.
     * @param  field A Calendar constant to retrieve the field value from the Date
     * object.
     * @return The value of the field that is requested.
     * @throws ArrayIndexOutOfBoundsException - if specified field is out of
     * range (<code>field</code> &lt; 0 || <code>field</code> &gt;= <code>Calendar.FIELD_COUNT</code>).
     * @see java.util.Calendar
     */
    public static int get(Date date, int field) {

        Calendar cal = Calendar.getInstance();

        cal.setTime(date);

        int value = cal.get(field);

        // Add 1 if the field is Calendar.MONTH since Calendar returns
        // the month value starting from 0.
        if (Calendar.MONTH == field)
            value += 1;

        // If it is 12 am/pm, the value will be 0. Need to change it to 12 for ease of display.
        if (Calendar.HOUR == field && value == 0)
            value = 12;

        return value;
    }
}

Related

1. age(Date dob)
2. age(int year, int month, int date)
3. ageAcceptable(final Date doB, final Date now, final int acceptedAge)
4. ageInYears(java.util.Date dateUtil)