Question

I got a little problem with a JOptionPane which I use to warn user if wrong input is found. It works correct first time. But when I close down the JFrame which calls for that JOptionPane, and open it again it will this time call for it twice. And it will stack for every close down I do.

I have tried to look for the problem without any luck. I can provide the code, but it is quite large though.

Third EDIT: I have found and solved the problem now.

Ok, I provided the code I use. I have cut it down so it only show the necessary one. I dont think it will compile, but this is how I use the addActionListener();

public class BorderLayoutDemo extends JFrame implements ActionListener {

    private JButton button1 = new JButton("L?gg till kund");
    private JButton button2 = new JButton("Ta bort kund");
    private JButton button3 = new JButton("Visa kund");
    private JButton button4 = new JButton("Lista alla kunder");
    private JButton button5 = new JButton("Avsluta");
    private JButton button6 = new JButton("Change");

    private JTextArea TextWindow = new JTextArea("Hej\nHej\nHej\nHej\nHej\nHej\nHej\nHej\nHej\nHej\nHej\nHej\nHej\n");
    private JScrollPane scrollPane = new JScrollPane(TextWindow);   //l?gger in TextWindow s? att det f?r en scroll-bar

    private JPanel aPanel = new JPanel();
    private JFrame aFrame = new JFrame();

    private JTextField aTextfield1 = new JTextField();
    private JTextField aTextfield2 = new JTextField();

    private JButton aButton1 = new JButton("L?gg till kund");
    private JButton aButton2 = new JButton("St?ng");

    public BorderLayoutDemo() {

            setTitle("Bankregister");

            setLayout(new BorderLayout());

            JPanel panel = new JPanel();
            panel.setBorder(BorderFactory.createEmptyBorder(0, 0, 0, 10));
            panel.setLayout(new GridLayout(6,1,55,5)); //row, cols, hgap, vgap

            button1.addActionListener(this);
            button2.addActionListener(this);
            button3.addActionListener(this);
            button4.addActionListener(this);
            button5.addActionListener(this);
            button6.addActionListener(this);

            panel.add(button1);
            panel.add(button2);
            panel.add(button3);
            panel.add(button4);
            panel.add(button5);
            panel.add(button6);

            JPanel panel2 = new JPanel();
            panel2.add(panel);

            add(panel2,BorderLayout.WEST);
            add(scrollPane,BorderLayout.CENTER);

            setJMenuBar(menu());

            setSize(600,300);

            setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            setLocationRelativeTo(null);
            setVisible(true);

    }

    public void addCustomer(boolean status) {


            if(status) {    

                aFrame.setTitle("L?gg till kund");
                aFrame.setSize(200,300);
                aFrame.setLayout(new GridLayout(3,1));

                aPanel.setLayout(new GridLayout(2,1)); //rad, kolumn

                aPanel.add(aTextfield1);
                aPanel.add(aTextfield2);

                aButton1.addActionListener(this);
                aButton2.addActionListener(this);
                System.out.println("Foo!!!!!!!!!!!!!");

                aFrame.add(aPanel);
                aFrame.add(aButton1);
                aFrame.add(aButton2);

                aFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                aFrame.setLocationRelativeTo(null);
                aFrame.setVisible(true);
            }
            else {

                aFrame.setVisible(false);


            }
    }

    public static void main(String[] args) {

        new BorderLayoutDemo();
    }

    public void actionPerformed(ActionEvent e) {
        if(e.getSource() == button1) {
            setEnabled(false);
            addCustomer(true);
        }

        //IFs f?r addCustomer();
        else if(e.getSource() == aButton1) {

            if((aTextfield1.getText().isEmpty() || aTextfield2.getText().isEmpty())) {
                JOptionPane.showMessageDialog(null, "You miss to fill out the fields");
            }
            else {
                JOptionPane.showMessageDialog(null, "Added");
                Kund kund = new Kund(aTextfield1.getText(),aTextfield2.getText());
                setEnabled(true);
                register.add(kund);
            }
        }
        else if(e.getSource() == aButton2) {
            setEnabled(true);
            addCustomer(false);
        }

Answer 1

Sounds like you are adding the “validation listener” every time you open the JFrame. So check your “addListenerXXX” code to make sure it is only added/created once.

Which also leads to the question why are you using a JFrame for this? Typically an application has a single JFrame. Then, if you need a window to enter data you create a JDialog.