Как Записать Слушателю Внутренней рамки

public class InternalFrameEventDemo ...
                     implements InternalFrameListener ... {
    ...

    public void internalFrameClosing(InternalFrameEvent e) {
        displayMessage("Internal frame closing", e);
    }

    public void internalFrameClosed(InternalFrameEvent e) {
        displayMessage("Internal frame closed", e);
        listenedToWindow = null;
    }

    public void internalFrameOpened(InternalFrameEvent e) {
        displayMessage("Internal frame opened", e);
    }

    public void internalFrameIconified(InternalFrameEvent e) {
        displayMessage("Internal frame iconified", e);
    }

    public void internalFrameDeiconified(InternalFrameEvent e) {
        displayMessage("Internal frame deiconified", e);
    }

    public void internalFrameActivated(InternalFrameEvent e) {
        displayMessage("Internal frame activated", e);
    }

    public void internalFrameDeactivated(InternalFrameEvent e) {
        displayMessage("Internal frame deactivated", e);
    }

    void displayMessage(String prefix, InternalFrameEvent e) {
        String s = prefix + ": " + e.getSource(); 
        display.append(s + newline);
    }

    public void actionPerformed(ActionEvent e) {
        if (SHOW.equals(e.getActionCommand())) {
            ...
            if (listenedToWindow == null) {
                listenedToWindow = new JInternalFrame("Event Generator",
                                                      true,  //resizable
                                                      true,  //closable
                                                      true,  //maximizable
                                                      true); //iconifiable
                //We want to reuse the internal frame, so we need to
                //make it hide (instead of being disposed of, which is
                //the default) when the user closes it.
                listenedToWindow.setDefaultCloseOperation(
                                        WindowConstants.HIDE_ON_CLOSE);

                listenedToWindow.addInternalFrameListener(this);
                ...
            }
        } 
        ...
    }
}