Java date to age

How to Easily Calculate Age from Date of Birth in Java using Calendar

Learn how to calculate age from date of birth in Java using Calendar. This blog post explores the best practices and methods for easily calculating age in Java.

• Overview of Age Calculation in Java
• Using LocalDate to Calculate Age
• How To Calculate Age From Date of Birth in Java
• Using Period Class to Calculate Age
• Using Joda Library to Calculate Age
• Best Practices for Age Calculation in Java
• Other helpful code examples for calculating age from date of birth in Java using Calendar
• Conclusion
• How is calendar age calculated?
• How do I calculate age in mm dd yyyy?
• How do you calculate age from date of birth logic?
• What is the fastest way to calculate age from date of birth?

Calculating age from date of birth is a common task in Java programming. Java provides several options for calculating age, including LocalDate, Period class, and Joda library. In this blog post, we will explore how to calculate age from date of birth in Java using Calendar.

Overview of Age Calculation in Java

Java offers several options for calculating age from date of birth, including LocalDate, Period class, and Joda library. The most common way to calculate age is by subtracting the birthdate from the current date. The implementation of calculating age in Java is portable across different versions.

Using LocalDate to Calculate Age

To calculate age using LocalDate, we can use the Years.yearsBetween() method. We can create a LocalDate object for the person’s birthdate and the current date. We can then use the yearsBetween() method to calculate the difference in years between the two dates. We can also use the Period class to calculate the difference in months and days.

Here’s an example code snippet that demonstrates how to use LocalDate to calculate age from date of birth in Java:

import java.time.LocalDate; import java.time.Period;public class AgeCalculator  public static int calculateAge(LocalDate birthDate, LocalDate currentDate)  return Period.between(birthDate, currentDate).getYears(); > > 

In the above code, we have created a static method calculateAge that takes two LocalDate objects as parameters. We then use the Period.between() method to calculate the difference between the two dates and get the years from the resulting Period object.

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Using Period Class to Calculate Age

To calculate age using Period class, we can use the Period.between() method. We can create a LocalDate object for the person’s birthdate and the current date. We can then use the between() method to calculate the difference between the two dates. We can get the days, months, and years from the Period object using the getDays() method.

Here’s an example code snippet that demonstrates how to use Period class to calculate age from date of birth in Java:

import java.time.LocalDate; import java.time.Period;public class AgeCalculator  public static void main(String[] args)  LocalDate birthDate = LocalDate.of(1990, 1, 1); LocalDate currentDate = LocalDate.now(); Period period = Period.between(birthDate, currentDate); int age = period.getYears(); System.out.printf("Age is %d years", age); > > 

In the above code, we have created a main method that calculates the age of a person born on January 1, 1990. We use the Period.between() method to calculate the difference between the birthdate and the current date and then get the years from the resulting Period object.

Using Joda Library to Calculate Age

Joda library offers more advanced features for date and time manipulation in java . We can use the Years.yearsBetween() method to calculate the difference in years between two dates. We can also use the Days.daysBetween() method to calculate the difference in days. We can create a LocalDate object for the person’s birthdate and the current date and convert them to Joda DateTime objects.

Here’s an example code snippet that demonstrates how to use Joda library to calculate age from date of birth in Java:

import org.joda.time.DateTime; import org.joda.time.Years;public class AgeCalculator  public static int calculateAge(DateTime birthDate, DateTime currentDate)  return Years.yearsBetween(birthDate, currentDate).getYears(); > > 

In the above code, we have created a static method calculateAge that takes two DateTime objects as parameters. We then use the Years.yearsBetween() method to calculate the difference in years between the two dates.

Best Practices for Age Calculation in Java

• It’s not recommended to use java.util.Date and java.util.Calendar anymore except for situations where you have to involve considerably large amounts of data.
• The date of birth is subtracted from the given date, which gives the age of the person.
• LocalDateTime can be used to calculate age with time included.
• You can create a method to calculate age in years , months, and days.
• You can also calculate age in total days only.
• You can use a scanner to input the date of birth.
• You can calculate age in hours, minutes, and seconds.
• You can use the ISO-8601 calendar system to calculate age.

Other helpful code examples for calculating age from date of birth in Java using Calendar

In java, java age from date code example

LocalDate today = LocalDate.now(); LocalDate birthday = LocalDate.of(1987, 09, 24);Period period = Period.between(birthday, today);//Now access the values as below System.out.println(period.getDays()); System.out.println(period.getMonths()); System.out.println(period.getYears());

Conclusion

Calculating age from date of birth is a common task in Java programming. Java provides several options for calculating age, including LocalDate, Period class, and Joda library. By following the best practices and using the appropriate method, we can easily calculate age from date of birth in Java using Calendar.

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Calculate Age from date of birth in Java

This tutorial demonstrates how to calculate the age from a birth date in Java. Something trivial as calculating the age, was daunting before Joda Time and Java 8. Let’s list the options you have to calculate the age from date of birth in Java.

Joda Time

import org.joda.time.LocalDate; import org.joda.time.Years; LocalDate birthday = new LocalDate(1989, 12, 6); LocalDate now = new LocalDate(2016, 10, 11); Years age = Years.yearsBetween(birthday, now); System.out.println("age: " + age.getYears()); // prints "age: 26"

Java 8

import java.time.LocalDate; import java.time.Month; import java.time.Period; import java.time.temporal.ChronoUnit; LocalDate birthday = LocalDate.of(1989, Month.DECEMBER, 6); LocalDate now = LocalDate.of(2016, Month.OCTOBER, 11); // using period Period period = Period.between(birthday, now); System.out.println(period.getDays()); System.out.println(period.getMonths()); System.out.println("age: " + period.getYears()); // prints "age: 26" // using chrono unit System.out.println("age: " + ChronoUnit.YEARS.between(birthday, now)); // prints "age: 26"

Plain Java

import java.util.Calendar; import java.util.Date; public static void main(String. args) < Calendar birthday = Calendar.getInstance(); birthday.set(1989, 12, 6); System.out.println("age: " + getAge(birthday.getTime())); // prints "age: 26" >public static int getAge(Date dateOfBirth) < Calendar today = Calendar.getInstance(); Calendar birthDate = Calendar.getInstance(); birthDate.setTime(dateOfBirth); if (birthDate.after(today)) < throw new IllegalArgumentException("You don't exist yet"); >int todayYear = today.get(Calendar.YEAR); int birthDateYear = birthDate.get(Calendar.YEAR); int todayDayOfYear = today.get(Calendar.DAY_OF_YEAR); int birthDateDayOfYear = birthDate.get(Calendar.DAY_OF_YEAR); int todayMonth = today.get(Calendar.MONTH); int birthDateMonth = birthDate.get(Calendar.MONTH); int todayDayOfMonth = today.get(Calendar.DAY_OF_MONTH); int birthDateDayOfMonth = birthDate.get(Calendar.DAY_OF_MONTH); int age = todayYear - birthDateYear; // If birth date is greater than todays date (after 2 days adjustment of leap year) then decrement age one year if ((birthDateDayOfYear - todayDayOfYear > 3) || (birthDateMonth > todayMonth)) < age--; // If birth date and todays date are of same month and birth day of month is greater than todays day of month then decrement age >else if ((birthDateMonth == todayMonth) && (birthDateDayOfMonth > todayDayOfMonth)) < age--; >return age; >

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Java date to age

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Java Program to Calculate Age from Birth Date

In this article you will see how to find age from given date of birth by using Java programming language.

Java Program to Calculate Age from Birth Date

Age of a person refers to the time period during which the person has lived. Generally we calculate the age of person from his date of birth to current date.

For example:

If the date of birth of a boy is 10th April 2005 and current date is 10th April 2015. That means the age of boy is 15 years old.

Let’s see different ways to calculate the age of a person from its’ date of birth.

Method-1: Java Program to Calculate Age from Birth Date by Using Java 8 Period Class

In Java 8, we have java.time.Period class which is used to measure a period of time in terms of years, months and days. Specifically it provides between() method by using which you can obtain a period of time having number of years, months and days between two date.

public static Period.between(Start_Date, End_Date);

• Take the input of your birth date in string format.
• Then convert that date to an instance of LocalDate class by using parse() method, which will be used as your start date.
• Create another instance of LocalDate class to get the current date by using now() method, which will be used as your end date during age calculation.
• The find the time period between your date of birth and current date by using between() method of period class, which is your age.
• Then print the age by using getYears() , getMonths() and getDays() method.

import java.util.Scanner; import java.time.LocalDate; import java.time.Period; public class Main < public static void main(String args[]) < //Scanner class object created Scanner sc = new Scanner(System.in); //Ask user to enter date of birth System.out.print("Enter birth date in yy-mm-dd format: "); //taking input from user String input = sc.nextLine(); //Get an instance of LocalDate class by using the parse() method, \ //here parameter is the inputted date in String format LocalDate birthDate = LocalDate.parse(input); //create an instance of LocalDate class by invoking the now() method //it will give you current date LocalDate currentDate = LocalDate.now(); //calculate the time period between your date of birth and current date //by using between() method of Period class if ((birthDate != null) && (currentDate != null)) < Period age = Period.between(birthDate, currentDate); System.out.print("Your Age: "); System.out.println(age.getYears()+" Years "+age.getMonths()+" Months "+age.getDays()+" Days"); >> >

Output: Enter birth date in yy-mm-dd format: 2000-04-10 Your Age: 21 Years 10 Months 21 Days

Method-2: Java Program to Calculate Age from Birth Date by Using ChronoUnit enum

In Java, java.time.temporal.ChronoUnit enum provides the standards units which are used in Java Date Time API. It also provides between() method which works similar to Period class.

• Take the input of your birth date in string format.
• Then convert that date to an instance of LocalDate class by using parse() method, which will be used as your start date.
• Create another instance of LocalDate class to get the current date by using now() method, which will be used as your end date during age calculation.
• The find the time period between your date of birth and current date by using between() method of ChronoUnit enum, which is your actual age.
• Then print the result.

import java.util.Scanner; import java.time.LocalDate; import java.time.temporal.ChronoUnit; public class Main < public static void main(String args[]) < //Scanner class object created Scanner sc = new Scanner(System.in); //Ask user to enter date of birth System.out.print("Enter birth date in yy-mm-dd format: "); //taking input from user String input = sc.nextLine(); //Get an instance of LocalDate class by using the parse() method, \ //here parameter is the inputted date in String format LocalDate birthDate = LocalDate.parse(input); //create an instance of LocalDate class by invoking the now() method //it will give you current date LocalDate currentDate = LocalDate.now(); //calculate the time period between your date of birth and current date //by using between() method of ChronoUnit enum if ((birthDate != null) && (currentDate != null)) < long years = ChronoUnit.YEARS.between(birthDate, currentDate); System.out.print("Your Age: "+years); >> >

Output: Enter birth date in yy-mm-dd format: 2000-04-10 Your Age: 21

Method-3: Java Program to Calculate Age from Birth Date by Using Calendar Class

• Pass your date of birth to constructor of Calendar class.
• Then get the difference between current year and birth year.
• If birth date month is greater than or equal to current date month and day of birth date is greater than day of current date then decrement age by 1.
• Print the final age.

import java.util.Calendar; import java.util.GregorianCalendar; public class Main < public static void main(String args[]) < //date of birth in yy-mm-dd format Calendar birthDate = new GregorianCalendar(2000, 04, 10); Calendar currentDate = new GregorianCalendar(); //got age in between year of date of birth and current year int age = currentDate.get(Calendar.YEAR) - birthDate.get(Calendar.YEAR); //But Decrementing age by 1, if birth date month is greater than or equal to current date month //and day of birth date is greater than day of current date if ((birthDate.get(Calendar.MONTH) >currentDate.get(Calendar.MONTH)) || (birthDate.get(Calendar.MONTH) == currentDate.get(Calendar.MONTH) && birthDate.get(Calendar.DAY_OF_MONTH) > currentDate.get(Calendar.DAY_OF_MONTH))) < //decrements age by 1 age--; >//prints the age System.out.println("Your current Age: "+age); > >

Output: Your current Age: 21

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