EvenEntryLoop.java

/*
asked on YA:

Can anyone code this Java program for me?
Write an application that asks a user to type an even number to continue or to type 999 to stop.
 When the user types an even number, display the message “Good job!” and then ask for another input.
 When the user types an odd number, display an error message and then ask for another input.
 When the user types 999, end the program. Use JOptionPane for the user input Save the file as EvenEntryLoop.java.

*/

import javax.swing.JOptionPane;

public class EvenEntryLoop {

    /**
    *   Program:    EvenEntryLoop.java
    *   Purpose:    Yahoo! Answers
    *   Creator:    Chris Clarke, author "50 Java Program Source Codes"
    *            & "50 More Java Source Codes" available in paperback
    *            & e-book at ridiculously low prices from amazon.co.uk
    *   Created:    18.02.2015
    */

    public static void main(String[] args) {

        final int SENTINEL = 999;
        JOptionPane pane = new JOptionPane();
        int number = 0;

        do {
            try {
                number = Integer.parseInt( pane.showInputDialog(
                 "Please type an even number, or type 999 to stop."));
            } catch (NumberFormatException e) {
                pane.showMessageDialog( null, "Error! That isn't a whole number!");
                continue;
            } // try

            if (number==SENTINEL) System.exit(0);

            if (number%2==0) {
                pane.showMessageDialog( null, "Good job!");
            } else {
                pane.showMessageDialog( null, "Error! That isn't an even number.");
            } // if

        } while (true);

    } // main()

} // class EvenEntryLoop