We showed a login form HERE and now it's time to see it in action. The key aspects of the code are

  1. Overriding the allow method of the AuthenticatingForm class
  2. Adding the 'real application gui' to the Container that is the content pane, activated upon successful login.
import java.awt.*;
import java.awt.event.*;

import java.io.*;

import java.util.*;

import javax.swing.*;


public abstract class AuthenticatingFrame extends JFrame {
    public static final String MAIN_PANEL = "main";
    public static final String LOGIN_PANEL = "login";
    private JPanel cards;
    private JPanel contentPane;
    private LoginForm loginForm;

    private void setGui() {
        try {
            setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            cards = new JPanel(new CardLayout());
            setContentPane(cards);
            loginForm = new LoginForm(new Authenticator());
            contentPane = new JPanel();
            cards.add(loginForm, LOGIN_PANEL);
            cards.add(contentPane, MAIN_PANEL);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Return the Container that is shown when
     * successful login has occurred
     *
     * @return The main, authenticated content pane Container
     */
    @Override
        public Container getContentPane() {
            return contentPane;
        }

    /**
     * Testing purposes - here follows an example usage
     *
     * @param args DOCUMENT ME!
     */
    public static void main(String[] args) {
        try {
            SwingUtilities.invokeAndWait(new Runnable() {
                public void run() {
                    AuthenticatingFrame f = new AuthenticatingFrame() {
                        // Override allow, per spec
                        public boolean allow(String username, char[] pw) {
                            // An example of the worst kind of credential practice
                            return "admin".equals(username) && "admin".equals(new String(pw));
                        }
                    };
                    f.setGui();
                    f.getContentPane()
                .add(new JLabel("Congratulations - you're logged in!"));
            f.pack();
            f.setVisible(true);
                }
            });
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * This is the method that authenticates the user,
     * called by the login Action and this must be overridden appropriately
     *
     * @param userName The user name
     * @param password The password
     *
     * @return Whether login was successful
     */
    public abstract boolean allow(String userName, char[] password);

    private class Authenticator extends AbstractAction {
        /**
         * This Action authenticates the user and forwards
         * the focus to the main content pane if successful.
         * It does this by calling the allow method of the
         * containing frame.
         *
         * @param e The ActionEvent from the login button
         */
        public void actionPerformed(ActionEvent e) {
            if (allow(loginForm.getUserName(), loginForm.getPassword())) {
                CardLayout cl = (CardLayout) (cards.getLayout());
                cl.show(cards, MAIN_PANEL);
            } else {
                System.out.println("FAILED");
            }
        }
    }
}
The source code is HERE.