Java LocalDate withDayOfYear Method

Introduction

In this lab, we will learn how to use the withDayOfYear() method in Java LocalDate class to create a date with a new day-of-year value.

Create a Java file

Create a file LocalDateWithDayOfYear.java under the ~/project directory with the following code:

import java.time.LocalDate;

public class LocalDateWithDayOfYear {
    public static void main(String[] args) {
        System.out.println("Original date: ");
        LocalDate localDate = LocalDate.of(2002, 01, 10);
        System.out.println(localDate);
    }
}

Use the following command to compile and run the code:

javac LocalDateWithDayOfYear.java && java LocalDateWithDayOfYear

The output should show the original date:

Original date:
2002-01-10

Use withDayOfYear() to Set the New Day-of-Year

To create a new date by setting a new value of a day-of-year, we can use the withDayOfYear() method to set a new day for the date.

Add the following code after the System.out.println(localDate); line:

// set day-of-year as 30
localDate = localDate.withDayOfYear(30);
System.out.println("New date with day-of-year set as 30: ");
System.out.println(localDate);

// set day-of-year as 300
localDate = localDate.withDayOfYear(300);
System.out.println("New date with day-of-year set as 300: ");
System.out.println(localDate);

Use the following command to compile and run the code:

javac LocalDateWithDayOfYear.java && java LocalDateWithDayOfYear

The output should show the new dates with the new day-of-year values:

Original date:
2002-01-10
New date with day-of-year set as 30:
2002-01-30
New date with day-of-year set as 300:
2002-10-27

Handle Invalid Date

If the resulting date is invalid, an exception will be thrown. We can handle the exception using try-catch block as follows:

try {
    // set day-of-year as 366 (invalid for non-leap year)
    localDate = localDate.withDayOfYear(366);
    System.out.println(localDate);
} catch (Exception e) {
    System.out.println("Invalid date: " + e.getMessage());
}

Use the following command to compile and run the code:

javac LocalDateWithDayOfYear.java && java LocalDateWithDayOfYear

The output should show the message of invalid date exception:

Original date:
2002-01-10
New date with day-of-year set as 30:
2002-01-30
New date with day-of-year set as 300:
2002-10-27
Invalid date: Invalid date 'DayOfYear 366' as '2002' is not a leap year

Summary

In this lab, we have learned how to use the withDayOfYear() method in Java LocalDate class to create a date with a new day-of-year value. We have also learned how to handle the invalid date exception when setting a new day-of-year value.