Question

I try build the 2 Class: LoginScreen Class and MainScreen Class

When I run program it will show the login screen first then I use username and password to login the Mainscreen are pop-up but the login screen doesn’t disappear.I am not sure how to handle it correctly.

Because the method I use is

public void actionPerformed(ActionEvent e) {
String cmd = e.getActionCommand();

   if (OK.equals(cmd)) { //Process the password.
       char[] input = passwordField.getPassword();
       if (isPasswordCorrect(input)) {
           javax.swing.SwingUtilities.invokeLater(new Runnable() {
               public void run() {
                  JFrameExample.main(null);
               }
           });
       } else {
           JOptionPane.showMessageDialog(controllingFrame,
               "Invalid password. Try again.",
               "Error Message",
               JOptionPane.ERROR_MESSAGE);
       }

       //Zero out the possible password, for security.
       Arrays.fill(input, '0');

       passwordField.selectAll();
       resetFocus();
   } else { //The user has asked for help.
       JOptionPane.showMessageDialog(controllingFrame,
           "You can get the password by searching this example's\n"
         + "source code for the string \"correctPassword\".\n"
         + "Or look at the section How to Use Password Fields in\n"
         + "the components section of The Java Tutorial.");
   }

}

I know this is the stupid code and wrong way to implement it but can you guide me to make the appropriate one.

Answer 1

I guess this method is a method of your first screen, which must be a JDialog or a JFrame. Just call setVisible(false) to hide the frame (you may also call dispose() if the dialog won’t be used anymore).

Also, you shouldn’t call the main method on JFrameExample. A main method is normally used to start a new application. Just do what the main method does from your action listener (probably new JFrameExample().setVisible(true)).

Finally, an event listener is always invoked in the event dispatch thread (EDT), so there is no point in using SwingUtilities.invokeLater from an event listener.

To recap, here’s how the code should look like:

if (isPasswordCorrect(input)) {
    setVisible(false); // or dispose();
    JFrame mainFrame = new JFrameExample();
    mainFrame.setVisible(true);
}