New to Java

Hi,

I have a JFrame window which pops up a dialog box at the time of pressing a menu item. Now in dialog box i have a login button which performs some processing and then closes the dialog box. But before closing it must change the title of parent window. I searched & found following commands:

            parentWind.invalidate();

            parentWind.validate();

            parentWind.repaint();

            parentWind.pack();

            parentWind.setVisible(true);

but they are not doing anything. I also found on this forum to use window listener:

addWindowListener(new WindowAdapter() { 

                    @Override 

                    public void windowClosing(WindowEvent e) { 

                        parentWind.setTitle("Login = bob");

            parentWind.invalidate();

            parentWind.validate();

            parentWind.repaint();

            parentWind.pack();

            parentWind.setVisible(true);

                    } 

                }); 

but addWindowListener(..) requires an object to invoke. I tried this & parentWind obj but it says cant find symbol constructor().

My dialog box code is given below:

class LoginDialog extends JDialog implements ActionListener{

        JFrame parentWind;

        JTextField userName = new JTextField();

        JTextField password = new JTextField();

        JLabel label = new JLabel("LOGIN");

        //JLabel label1 = new JLabel("TraineeID");

        JLabel label2 = new JLabel("Password");

        JButton btn = new JButton("Login");

        LoginDialog(JFrame parent,String title){

            super(parent,title,false);

            setLayout(new FlowLayout());

        //setSize(300, 200);

            //JOptionPane.showMessageDialog(null,"Inside LoginDialog");

            setSize(800,700);

            userName.setPreferredSize(new Dimension(130,30));

            password.setPreferredSize(new Dimension(130,30));

            label.setPreferredSize(new Dimension(30,30));

            label2.setPreferredSize(new Dimension(70,80));

            parentWind = parent;

            add(userName);

            add(label);

            add(label2);

            add(password);

            add(btn);

            //setVisible(true);

            btn.addActionListener(this);

        }

        public void actionPerformed(ActionEvent e){

            parentWind.addWindowListener(new WindowAdapter() { 

                    @Override 

                    public void windowClosing(WindowEvent e) { 

                        parentWind.setTitle("Login = bob");

            parentWind.invalidate();

            parentWind.validate();

            parentWind.repaint();

            parentWind.pack();

            parentWind.setVisible(true);

                    } 

                }); 

        }

}

.

Somebody please guide me.

Zulfi.