Java Program to Find Area of Octagon

import java.io.*;
class Main
{
    public static void main(String [] args)
    {
        //side length of octagon declared
        double s = 1;
        //finding area using formula
        double area  = 2*(1+Math.sqrt(2))*s*s;
        System.out.println("The area of octagon is: " + area);
    }
}

Output:

The area of octagon is: 4.82842712474619