Java Calculate Age from Calendar of Birth

Tags: Java Calendar DateUtil

In this Java tutorial, we learn how to calculate someone’s age based on their birthday as a Calendar object in Java programming language.

How to calculate age from Calendar of birth in Java

In this first step, we create a new Java class named DateUtil, and implement the static method named getAge(Calendar birthday), this method to calculate the number of age from a given Calendar object and current system Date as the following Java code.

DateUtil.java 

import java.util.Calendar;

public class DateUtil {

    /**
     * This method to calculate number of age from given birthday Calendar value.
     * @param birthday the Calendar of birth
     * @return number of age
     */
    public static int getAge(Calendar birthday) {
        Calendar todayCalendar = Calendar.getInstance();
        int age = todayCalendar.get(Calendar.YEAR) - birthday.get(Calendar.YEAR);
        return age;
    }

}

In the following example Java code, we learn how to use the DateUtil class above to calculate age from a given Calendar object in Java program.

GetAgeFromCalendarExample.java 

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

public class GetAgeFromCalendarExample {
    public static void main(String... args) {
        Calendar birthday = new GregorianCalendar(1988, Calendar.JULY, 11);

        // Calculate Age from Calendar of Birth
        int age = DateUtil.getAge(birthday);

        System.out.println("Today: " + new Date());
        System.out.println("Date of birth: " + birthday.getTime());
        System.out.println("Age: " + age);
    }
}
The output as below. 
Today: Thu Aug 18 22:57:24 ICT 2022
Date of birth: Mon Jul 11 00:00:00 ICT 1988
Age: 34

Happy Coding 😊

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