如何阻止另一个类的JComponent？

Question

I am trying to disable a JComponent from another class, similar to a modal dialogue. In my case, I'm invoking a JavaFX dialogue from a Swing component; more specifically a FileChooser . Since, for example, showOpenDialog expects an javafx.stage.Window as argument, passing the JComponent is not an option.

I tried using setEnabled(false) and setEnabled(true) , but this has a strange side effect: Upon invoking setEnabled(true) , the JFrame will be minimized. Invoking setVisible(true) solves this but causes the screen to “flash”, because the frame will still disappear for a short time.

The problem only occurs when I'm using a CountDownLatch to await the return of the file chooser, which is necessary because otherwise it would return immediately and I wouldn't be able to access the return value.

Here is a SSCCE to reproduce the issue:

public static void main(String[] args) {
    EventQueue.invokeLater(() -> {
        JFrame frame = new JFrame("Test");
        JButton button = new JButton("Click me!");
        JFXPanel jfxPanel = new JFXPanel();

        FileChooser fileChooser = new FileChooser();
        button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                frame.setEnabled(false);

                CountDownLatch latch = new CountDownLatch(1);
                Platform.runLater(() -> {
                    fileChooser.showOpenDialog(null);
                    latch.countDown();
                });

                try {
                    latch.await();
                } catch (InterruptedException ex) {
                    ex.printStackTrace();
                }

                frame.setEnabled(true);
            }

        });
        frame.add(button);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);
    });
}

Is there another option to block the component?

Answer 1

My answer is based on this article https://docs.oracle.com/javase/tutorial/uiswing/components/rootpane.html

The idea is that when FileChooser is opened we use custom GlassPane that intercepts all mouse events. It's not ideal solution, because you can still minimize, maximize and close underlying JFrame .

public class MyGlassPane extends JComponent implements PropertyChangeListener {
    public MyGlassPane() {
        CBListener listener = new CBListener();
        addMouseListener(listener);
        addMouseMotionListener(listener);
    }

    @Override
    public void propertyChange(PropertyChangeEvent evt) {
        setVisible(((Number) evt.getNewValue()).intValue() == 1);
    }
}

public class CBListener extends MouseInputAdapter {
    public void mouseMoved(MouseEvent e) {
        consume(e);
    }

    public void mouseDragged(MouseEvent e) {
        consume(e);
    }

    public void mouseClicked(MouseEvent e) {
        consume(e);
    }

    public void mouseEntered(MouseEvent e) {
        consume(e);
    }

    public void mouseExited(MouseEvent e) {
        consume(e);
    }

    public void mousePressed(MouseEvent e) {
        consume(e);
    }

    public void mouseReleased(MouseEvent e) {
        consume(e);
    }

    private void consume(MouseEvent e) {
        e.consume();
    }
}

With above classes you can put below FileChooser fileChooser = new FileChooser(); line code like this:

button.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {
        frame.firePropertyChange("disabled", 0, 1);
        Platform.runLater(() -> {
            fileChooser.showOpenDialog(null);
            frame.firePropertyChange("disabled", 1, 0);
        });
    }
});

MyGlassPane mgp = new MyGlassPane();
frame.setGlassPane(mgp);
frame.addPropertyChangeListener("disabled", mgp);