JFrame crashes when trying to replace a panel with another panel

Question

I have a JFrame which is initialized as follows:

setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
setPreferredSize(PREFERRED_SIZE);
setTitle("Game Set");

setLayout(new BorderLayout());
background = new JLabel(new ImageIcon("images/gameSetBackground.jpg"));
background.setPreferredSize(PREFERRED_SIZE);
add(background);

loginPane = new LoginPane();

background.setLayout(new GridBagLayout());
loginPane.setOpaque(false);
background.add(loginPane, constraints);

pack();
setVisible(true);

I did it this way because it let me set the background to the jpg I specify. Now I have the loginPane() class as follows:

public class LoginPane extends JPanel {
    JLabel label = new JLabel("Login");
    JLabel secondLabel = new JLabel("If you don't have a profile, click below to create one!");
    JTextField userName;
    JPasswordField password;

    public LoginPane() {
        setLayout(new GridBagLayout());

        userName = new JTextField(20);
        password = new JPasswordField(20);

        constraints.insets = new Insets(2, 2, 2, 2);
        constraints.gridx = 0;
        constraints.gridy = 0;
        add(label, constraints);

        // etc add all of them the same way

        constraints.gridy = 3;
        add(secondLabel, constraints);

        userName.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                password.requestFocus();
            }
        });

        password.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                if (userName.getText().equals("Mike")) {
                }
            }
        });
    }
}

What I want to happen is that when I hit enter after a username and password has been entered, I will check if that is a valid username/password pair. After that I want to remove everything here and display a different JPanel. Inside the password.ActionListener, I tried the following:

loginPane.removeAll();

background.removeAll();

Those were two separate cases, but both cause the JFrame to crash, the TextFields become unresponsive and I have to exit out. What am I doing wrong?

score 3 · Accepted Answer · edited May 23 '17 at 12:20

"JFrame crashes when trying to replace a panel with another panel"

Simple/and correct solution would be to use a CardLayout to switch between panels. See more at How to use CardLayout and see a simple example here.

The CardLayout has methods like show() to to show a certain panel by name, next() to show the next panel, and previous() to show the previous panel. This is preferred way, over removing and adding panels.

JFrame crashes when trying to replace a panel with another panel

1 Answers1