OffsetDateTime withDayOfMonth() method in Java with examples

The withDayOfMonth() method of OffsetDateTime class in Java returns a copy of this OffsetDateTime with the day-of-month altered as specified in the parameter.

Syntax:

public OffsetDateTime withDayOfMonth(int dayOfMonth)

Parameter: This method accepts a single parameter dayOfMonth which specifies the day-of-month to be set in the result which can range from 1 to 28-31.

Return Value: It returns a OffsetDateTime based on this date with the requested day and not null.

Exceptions: The program throws a DateTimeException when the day-of-month value is invalid or if the day-of-month is invalid for the month of that particular year.

Below programs illustrate the withDayOfMonth() method:

Program 1:

// Java program to demonstrate the withDayOfMonth() method

import java.time.OffsetDateTime;

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

        // Parses the date1
        OffsetDateTime date1
            = OffsetDateTime
                  .parse(
                      "2018-12-12T13:30:30+05:00");

        // Prints dates
        System.out.println("Date1: " + date1);

        // Changes the day of month
        System.out.println("Date1 after altering day-of-month: "
                           + date1.withDayOfMonth(20));
    }
}

Output:

Date1: 2018-12-12T13:30:30+05:00
Date1 after altering day-of-month: 2018-12-20T13:30:30+05:00

Program 2 :

// Java program to demonstrate the withDayOfMonth() method

import java.time.OffsetDateTime;

public class GFG {
    public static void main(String[] args)
    {
        try {
            // Parses the date1
            OffsetDateTime date1
                = OffsetDateTime
                      .parse(
                          "2018-12-12T13:30:30+05:00");

            // Prints dates
            System.out.println("Date1: " + date1);

            // Changes the day of month
            System.out.println("Date1 after altering day-of-month: "
                               + date1.withDayOfMonth(32));
        }
        catch (Exception e) {
            System.out.println("Exception: " + e);
        }
    }
}

Output:

Date1: 2018-12-12T13:30:30+05:00
Exception: java.time.DateTimeException:
           Invalid value for DayOfMonth (valid values 1 - 28/31): 32

Reference: https://docs.oracle.com/javase/10/docs/api/java/time/OffsetDateTime.html#withDayOfMonth(int)