LocalDate plusMonths() method in Java with Examples

The plusMonths() method of LocalDate class in Java is used to add the number of specified months in this LocalDate and return a copy of LocalDate.

This method adds the months field in the following steps:

• Add the months to the month-of-year field.
• Check if the date after adding months is valid or not.
• If date is invalid then method adjust the day-of-month to the last valid day.

For example, 2018-08-31 plus one month gives date 2018-09-31 but this is invalid result, so the last valid day of the month, 2018-09-30, is returned.This instance is immutable and unaffected by this method call.

Syntax:

public LocalDate plusMonths(long monthsToAdd)

Parameters: This method accepts a single parameter monthsToAdd which represents the months to add, may be negative.

Return Value: This method returns a LocalDate based on this date with the months added, not null.

Exception: This method throws DateTimeException if the result exceeds the supported date range.

Below programs illustrate the plusMonths() method:
Program 1:

// Java program to demonstrate
// LocalDate.plusMonths() method

import java.time.*;

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

        // create a LocalDate object
        LocalDate date
            = LocalDate.parse("2018-11-13");

        // print instance
        System.out.println("LocalDate before"
                           + " adding months: " + date);

        // add 5 months
        LocalDate returnvalue
            = date.plusMonths(5);

        // print result
        System.out.println("LocalDate after "
                           + " adding months: " + returnvalue);
    }
}

Output:

LocalDate before adding months: 2018-11-13
LocalDate after  adding months: 2019-04-13

Program 2:

// Java program to demonstrate
// LocalDate.plusMonths() method

import java.time.*;

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

        // create a LocalDate object
        LocalDate date
            = LocalDate.parse("2018-12-31");

        // print instance
        System.out.println("LocalDate before"
                           + " adding months: " + date);

        // add 9 months
        LocalDate returnvalue
            = date.plusMonths(9);

        // print result
        System.out.println("LocalDate after "
                           + " adding months: " + returnvalue);
    }
}

Output:

LocalDate before adding months: 2018-12-31
LocalDate after  adding months: 2019-09-30

References:
https://docs.oracle.com/javase/10/docs/api/java/time/LocalDate.html#plusMonths(long)