Year atDay() method in Java

The atDay() method of Year class in Java combines the current year with a day-of-year passed as parameter to it to create a LocalDate.

Syntax: 

public LocalDate atDay(int dayOfYear)

Parameter: This method accepts a single parameter dayOfYear. It is the day-of-year to use. It can take values from 1 to 365-366.

Return Value: It returns a Local Date formed by the current year and a date of year passed as parameter to the function.

Exception: This method throws a DateTimeException, if the day of year passed in the parameter is not valid, that is zero or less, 366 or greater or equal to 366 and the current year is not a leap year.

Below programs illustrate the atDay() method of Year in Java: 

Program 1:  

Java

// Program to illustrate the atDay() method

import java.util.*;
import java.time.*;

public class GfG {
    public static void main(String[] args)
    {

        // Creates a Year object
        Year thisYear = Year.of(2017);

        // Creates a local date with this
        // Year object and day passed to it
        LocalDate date = thisYear.atDay(31);

        System.out.println(date);
    }
}

Output:

2017-01-31

Program 2: To illustrate Exception. 

Java

// Program to illustrate the atDay() method

import java.util.*;
import java.time.*;

public class GfG {
    public static void main(String[] args)
    {

        // Creates a Year object
        Year thisYear = Year.of(2017);

        // Creates a local date with this
        // Year object and day passed to it
        try {
            LocalDate date = thisYear.atDay(367);
            System.out.println(date);
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

Output:

java.time.DateTimeException: Invalid value for DayOfYear (valid values 1 - 365/366): 367

Reference: https://docs.oracle.com/javase/8/docs/api/java/time/Year.html#atDay-int-