How do I close a JDialog and have the Window Event Listeners be notified?

问题

Is there a way to close a JDialog through code such that the Window event listeners will still be notified? I've tried just setting visible to false and disposing, but neither seem to do it.

回答1:

Closing a window (with dispose()) and hiding it (with setVisible(false)) are different operations, and produce different events -- and closing it from the operating system is yet another different operation that produces yet a different event.

All three will produce windowDeactivated to tell you the window's lost focus, but dispose() will then produce windowClosed, while closing from the OS will first produce windowClosing. If you want to handle both of these the same way, you can set the window to be disposed when closed:

window.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);

In general, setVisible(false) implies that you might want to use the window again, so it doesn't post any window events (apart from windowDeactivated). If you want to detect the hiding of a window, you need to use a ComponentListener;

window.addComponentListener(new ComponentAdapter() {
  @Override
  public void componentHidden(ComponentEvent e) {
    System.out.println("componentHidden()");
  }
})

Note though that this will pretty much only work for explicit setVisible() calls. If you need to detect hiding more generally, you can use a HierarchyListener, but it's probably more trouble than it's worth.

  window.addHierarchyListener(new HierarchyListener() {
    @Override
      public void hierarchyChanged(HierarchyEvent e) {
        System.out.println("valid: " + window.isValid());
        System.out.println("showing: " + window.isShowing());
      }
  });

Note that when you dispose a window you'll get a couple of HierarchyEvents, first for hiding and then for invalidation, but when you hide it with setVisible() it's still valid, so you won't get the invalidation.

回答2:

I don't seem to have your problem. When I use the code below windowDeactivated() is called for either setVisible( false ) or dispose() and windowClosed() is also called for dispose().

ClosingDialog.java:

public class ClosingDialog extends JDialog {
    public ClosingDialog(Frame owner, String title, boolean modal) {
        super(owner, title, modal);
        JPanel contentPanel = (JPanel) this.getContentPane();

        JButton setVisButton = new JButton("setVisible( false )");
        setVisButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                ClosingDialog.this.setVisible(false);
            }
        });

        JButton disposeButton = new JButton("dispose()");
        disposeButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                ClosingDialog.this.dispose();
            }
        });

        contentPanel.setLayout(new FlowLayout());

        contentPanel.add(setVisButton);
        contentPanel.add(disposeButton);

        this.addWindowListener(new WindowListener() {
            public void windowActivated(WindowEvent e) {
                System.out.println("windowActivated");
            }

            public void windowClosed(WindowEvent e) {
                System.out.println("windowClosed");
            }

            public void windowClosing(WindowEvent e) {
                System.out.println("windowClosing");
            }

            public void windowDeactivated(WindowEvent e) {
                System.out.println("windowDeactivated");
            }

            public void windowDeiconified(WindowEvent e) {
                System.out.println("windowDeiconified");
            }

            public void windowIconified(WindowEvent e) {
                System.out.println("windowIconified");
            }

            public void windowOpened(WindowEvent e) {
                System.out.println("windowOpened");
            }
        });

        this.setSize(300, 300);
    }
}

回答3:

Dispatch a windowClosing event to the Window. Check out the ExitAction example from the Closing an Application entry.

回答4:

Untested suggestion:

Have you tried getWindowListeners() and then iterating around to fire windowClosed() to each of the WindowListeners?

EDIT: the above suggestion is wrong. Keeping it for posterity.

I'm afraid calling dialog.dispose() works fine for me in my simple example.

回答5:

I wanted to fire a windowClosing event from the code (just as if the user clicked the X), because I have an extra close button in the JDialog and want the same WindowListener (that I implemented using a WindowAdapter) to be run when the X is clicked and when the button is clicked. Running dispose() only fires windowClosed, not windowClosing, and I want a message to appear before the window is closed, for confirmation. I also didn't manage to fire windowClosing via JDialog's method processWindowEvent since it is protected.

Here is how I got it working though:

WindowAdapter adapter = (WindowAdapter)jdialog.getWindowListeners()[0];
adapter.windowClosing(new WindowEvent((Window)jdialog, WindowEvent.WINDOW_CLOSING));

Hope that helps someone.

来源：https://stackoverflow.com/questions/1343542/how-do-i-close-a-jdialog-and-have-the-window-event-listeners-be-notified

标签

java

swing

jdialog