GCD.java Source code

Introduction

Here is the source code for GCD.java

Source

//package numeric;

/**
* This class calculates the Greatest Common
* Divisor of two numbers passed into the program
* through command line arguments.
*
* @author Alex Laird
* @version 1.0
* File: GCD.java
* Created: Sep 2008
*/
public class GCD {
    /**
    * Returns the Greatest Common Divisor of two
    * numbers that are passed into the method.
    *
    * @param a the first integer for comparison.
    * @param b the second integer for comparison.
    * @throws NegativeNumberException if the input given is negative.
    * @returns the Greatest Common Divisor.
    */
    public static int gcd(int a, int b) throws Exception {
        // throw an exception if the input is negative
        if (a < 0 || b < 0) {
            throw new Exception("The user has entered a " + "negative number.");
        }

        if (b == 0)
            return a;
        else
            return gcd(b, a % b);
    }

    /**
    * The main method from which the program executes;
    * it handles all I/O and method execution.
    *
    * @param args Arguments received from the command line (two numbers).
    * @param gcd The calcuated Greatest Common Divisor of args[0] and args [1].
    */
    public static void main(String[] args) {
        // ensure the user only enters two arguments
        if (args.length == 2) {
            // ensure the users arguments are numbers
            try {
                // calculate gcd
                int gcd = gcd(Integer.parseInt(args[0]), Integer.parseInt(args[1]));

                System.out.println(
                        "The Greatest Common Divisor of " + args[0] + " and " + args[1] + " is " + gcd + ".");
            } catch (NumberFormatException c) {
                System.out.println("Your arguments must be in " + "the form of integers when "
                        + "running the program (ex. " + "enter 'java numeric.GCD " + "50 30').");
            } catch (Exception c) {
                // used only in GUI
            }

        } else {
            System.out.println("Enter two numbers as arguments " + "when running the program (ex. "
                    + "enter 'java numeric.GCD 50 30').");
        }
    }
}