YearMonth format() method in Java

The format() method of YearMonth class in Java is used to format this YearMonth instance according to a specified DateTimeFormatter for year-month passed as parameter to this method.

Syntax: 

public String format(DateTimeFormatter formatter)

Parameter: This method accepts a single parameter formatter which is the DateTimeFormatter according to which this YearMonth instance will be formatted.
Return Value: It returns the value of this YearMonth as a string after formatting it according to the specified formatter.
Below programs illustrate the format() method of YearMonth in Java: 
Program 1:  

Java

// Program to illustrate the format() method

import java.util.*;
import java.time.*;
import java.time.format.DateTimeFormatter;

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

        // Create a YearMonth object
        YearMonth thisYearMonth = YearMonth.of(2017, 8);

        // Create a DateTimeFormatter string
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yy/MM");

        // Format this year-month
        System.out.println(thisYearMonth.format(formatter));
    }
}

Output:

17/08

Program 2: 

Java

// Program to illustrate the format() method

import java.util.*;
import java.time.*;
import java.time.format.DateTimeFormatter;

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

        // Create a YearMonth object
        YearMonth thisYearMonth = YearMonth.of(2018, 5);

        // Create a DateTimeFormatter string
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MM/yy");

        // Format this year-month
        System.out.println(thisYearMonth.format(formatter));
    }
}

Output:

05/18

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