public Period withMonths(int numberOfMonths)

// Java code to demonstrate withMonths() method
  
import java.time.Period;
  
class GFG {
    public static void main(String[] args)
    {
  
        // Get the String to be withMonthsd
        String period = "P1Y2M21D";
  
        // Parse the String into Period
        Period p = Period.parse(period);
  
        System.out.println("Period: " + p);
  
        // Get the number of months
        int numberOfMonths = 5;
  
        // Change the numberOfMonths of this Period
        // using withMonths() method
        System.out.println("New Period: "
                           + p.withMonths(numberOfMonths));
    }
}

Period: P1Y2M21D
New Period: P1Y5M21D

// Java code to demonstrate withMonths() method
  
import java.time.Period;
  
class GFG {
    public static void main(String[] args)
    {
  
        // Get the String to be withMonthsd
        String period = "-P1Y2M21D";
  
        // Parse the String into Period
        Period p = Period.parse(period);
  
        System.out.println("Period: " + p);
  
        // Get the number of months
        int numberOfMonths = -5;
  
        // Change the numberOfMonths of this Period
        // using withMonths() method
        System.out.println("New Period: "
                           + p.withMonths(numberOfMonths));
    }
}

Period: P-1Y-2M-21D
New Period: P-1Y-5M-21D