Interface Issue

public class Interface extends JFrame implements ActionListener {

    private Container contentPane;

    private JPanel buttonPanel, userPanel;

    private JButton loginButton, createUserButton, logoutButton, withdrawButton, depositButton, switchToRegisterButton, switchToLoginButton;

    private JLabel headerLabel, inputTopJTFLabel, inputPW1JPFLabel, toastLabel, inputPW2JPFLabel;

    public JTextField inputTopJTF;
    public JPasswordField inputPW1JPF, inputPW2JPF;

    JRootPane rootPane;

    public Interface(int width, int height, String title) {

        //Setting up Interface
        setTitle(title);
        setSize(width, height);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocation(100,100);
        setVisible(true);

        Font header = new Font("TimesRoman", Font.PLAIN, 50);

        ///////////////////////BUTTON PANEL///////////////////////

        //Button Panel
        buttonPanel = new JPanel();

        //Buttons
        //loginButton
        loginButton = new JButton("Login");
        loginButton.addActionListener(this);
        loginButton.setAlignmentX(Component.CENTER_ALIGNMENT);

        //switchToRegisterButton
        switchToRegisterButton = new JButton("New User?");
        switchToRegisterButton.addActionListener(this);
        switchToRegisterButton.setAlignmentX(Component.CENTER_ALIGNMENT);

        //switchToLoginButton
        switchToLoginButton = new JButton("Switch to Login");
        switchToLoginButton.addActionListener(this);
        switchToLoginButton.setAlignmentX(Component.CENTER_ALIGNMENT);
        switchToLoginButton.setVisible(false);

        //createUserButton
        createUserButton = new JButton("Register");
        createUserButton.addActionListener(this);
        createUserButton.setAlignmentX(Component.CENTER_ALIGNMENT);
        createUserButton.setVisible(false);

        //logoutButton
        logoutButton = new JButton("Logout");
        logoutButton.addActionListener(this);
        logoutButton.setAlignmentX(Component.CENTER_ALIGNMENT);
        logoutButton.setVisible(false);

        //withdrawButton
        withdrawButton = new JButton("Withdraw");
        withdrawButton.addActionListener(this);
        withdrawButton.setAlignmentX(Component.CENTER_ALIGNMENT);
        withdrawButton.setVisible(false);

        //depositButton
        depositButton = new JButton("Deposit");
        depositButton.addActionListener(this);
        depositButton.setAlignmentX(Component.CENTER_ALIGNMENT);
        depositButton.setVisible(false);

        //Adding items to buttonPanel
        buttonPanel.add(loginButton);
        buttonPanel.add(switchToRegisterButton);
        buttonPanel.add(switchToLoginButton);
        buttonPanel.add(createUserButton);
        buttonPanel.add(logoutButton);
        buttonPanel.add(withdrawButton);
        buttonPanel.add(depositButton);

        ///////////////BODY PANEL//////////////////////

        //Body Panel
        userPanel = new JPanel();
        userPanel.setLayout(new BoxLayout(userPanel, BoxLayout.PAGE_AXIS));

        //JTextFields
        //inputTopJTF
        Dimension inputTopJTFDimension = new Dimension(100, 20);
        inputTopJTF = new JTextField();
        inputTopJTF.setMaximumSize(inputTopJTFDimension);

        //inputPW1JPF
        Dimension inputPW1JPFDimension = new Dimension(100, 20);
        inputPW1JPF = new JPasswordField();
        inputPW1JPF.setMaximumSize(inputPW1JPFDimension);

        //inputPW2JPF
        Dimension inputPW2JPFDimension = new Dimension(100, 20);
        inputPW2JPF = new JPasswordField();
        inputPW2JPF.setMaximumSize(inputPW2JPFDimension);
        inputPW2JPF.setVisible(false);

        //JLabels
        //toastLabel
        toastLabel = new JLabel("Please sign in or create new account.");
        toastLabel.setAlignmentX(Component.CENTER_ALIGNMENT);

        //inputTopJTFLabel
        inputTopJTFLabel = new JLabel("Username:");
        inputTopJTFLabel.setAlignmentX(Component.CENTER_ALIGNMENT);

        //inputPW1JPFLabel
        inputPW1JPFLabel = new JLabel("Password:");
        inputPW1JPFLabel.setAlignmentX(Component.CENTER_ALIGNMENT);

        //inputPW2JPFLabel
        inputPW2JPFLabel = new JLabel("Confirm Password:");
        inputPW2JPFLabel.setAlignmentX(Component.CENTER_ALIGNMENT);
        inputPW2JPFLabel.setVisible(false);

        //Adding items to userPanel
        userPanel.add(toastLabel);
        userPanel.add(inputTopJTFLabel);
        userPanel.add(inputTopJTF);
        userPanel.add(inputPW1JPFLabel);
        userPanel.add(inputPW1JPF);
        userPanel.add(inputPW2JPFLabel);
        userPanel.add(inputPW2JPF);

///////////////CONTENT PANE/////////////////////

    //Content Pane
    contentPane = getContentPane();

    //JLabels
    //headerLabel
    headerLabel = new JLabel("Bank", SwingConstants.CENTER);
    headerLabel.setFont(header);

    //PAGE_START
    contentPane.add(headerLabel, BorderLayout.PAGE_START);

    //LINE_START

    //CENTER
    contentPane.add(userPanel, BorderLayout.CENTER);

    //LINE_END

    //PAGE_END
    contentPane.add(buttonPanel, BorderLayout.PAGE_END);

    userPanel.setFocusable(true);
    userPanel.requestFocus();

    //Default Button
    rootPane = getRootPane();
    rootPane.setDefaultButton(loginButton);

    }