Recursively doing factorial mathematics with Java

import java.util.Scanner;
/**
 * This demonstrates calling methods recursively in a language
 * called Java. It does a factorial calculation.
 * @Author: Shaun B
 * @Version: 2012-08-13
 **/
public class recursive
{
    // Java seems a little more pedantic and it took me a few minutes of
    // actual thinking to convert this from the much easier to understand
    // programming language 'C'.
    private static long number=0;
    private static long returnValue=0;
    // There are probably better ways to read in keyboard inputs, but this
    // works, so...
    private static Scanner keyboardBuffer=new Scanner (System.in);
    // Our main function:
    public static void main (String args[])
    {
        // User prompts:
        System.out.println ("This is an example of recursive programming");
        System.out.println ("Please enter a whole positive number to see");
        System.out.print ("see its' factorial value, ");
        System.out.println ("or type 0 (zero) to exit.");
        System.out.print ("C:\\>");
        number=keyboardBuffer.nextInt();
        // Checks for zero to exit:
        if (number==0)
        {
            System.out.println ("\n\nHave a nice day :-)");
            return;
        }
        // Converts a negative to a positive number (not sure if it'd make any
    // actual difference though...)
        if (number<0)
        {
            number=-number;
        }
        // Calls the recursive function factorial, sending the entered number to it
        // and storing the returned value in the variable returnValue:
        returnValue=factorial (number);
        System.out.format ("And the answer is %d\n",returnValue);
        // Restarts the program:
        number=0;
        returnValue=0;
        recursive.main (null);
    }
    public static long factorial (long n)
    {
        // Break case:
        if (n==1)
        {
            return n;
        }
        else
        {
            // Calls 'method' recursively:
            return n*factorial (n-1);
        }
    }
}