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YearMonth atDay() method in Java

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

Syntax:  

public LocalDate atDay(int dayOfMonth)

Parameter: This method accepts a single parameter dayOfMonth. It is the day-of-month to use. It can take values from 1 to 31.

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

Exception: This method throws a DateTimeException, if the day of month passed in the parameter is not valid.

Below programs illustrate the atDay() method of YearMonth 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 YearMonth object
        YearMonth thisYearMonth = YearMonth.of(2017, 8);
 
        // Creates a local date with this
        // YearMonth object and day passed to it
        LocalDate date = thisYearMonth.atDay(31);
 
        System.out.println(date);
    }
}


Output: 

2017-08-31

 

Program 2: To illustrate Exception. The below program throws an exception as September is of 30 days and not 31 days. 

Java




// Program to illustrate the atDay() method
 
import java.util.*;
import java.time.*;
 
public class GfG {
    public static void main(String[] args)
    {
 
        // Creates a YearMonth object
        YearMonth thisYearMonth = YearMonth.of(2017, 9);
 
        try {
            // Creates a local date with this
            // YearMonth object and day passed to it
            LocalDate date = thisYearMonth.atDay(31);
 
            System.out.println(date);
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}


Output: 

java.time.DateTimeException: Invalid date 'SEPTEMBER 31'

 

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

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