A calculator source code written in java

				/**				 * The main class of a simple calculator. Create one of these and you'll				 * get the calculator on screen.				 * 				 * @author David J. Barnes and Michael Kolling				 * @version 31 July 2000				 */				public class Calculator  				{				    private CalcEngine engine;				    private UserInterface gui;								    /**				     * Create a new calculator and show it.				     */				    public Calculator()				    {				        engine = new CalcEngine();				        gui = new UserInterface(engine);				    }								    /**				     * In case the window was closed, show it again.				     */				    public void show()				    {				        gui.setVisible(true);				    }				    				    public static void main(String [] args)				    {				        new Calculator().show();				    }				}