Partial modality

Question

Hi,
My project has a new requirement. We have two JFrames as part of the application, say Frame1 and Frame2. The requirement states that when any dialog is displayed via some interaction in Frame1, the dialog should be modal for Frame1, but not for Frame2. Therefore, while dialog 1 is displaying due to some click in Frame1, I should still be able to carry out some interactions in Frame2.
Is this even possible??? I have tried looking for modality on the site, but all I get is 'A modal dialog is one which blocks input to all other toplevel windows in the application, except for any windows created with the dialog as their owner'. Now does top level mean parent of dialog and all such ancestors, or all higher level windows, including all JFrames?
Any help in this matter appreciated.
Shefali.

Answer 1

Hi Tom,
You're welcome to the dukes!!! Anyways, a small problem. I used the code from one of the javatips, and implemented the following code. If you have the time, I'd really appreciate your helping me find out what's wrong...
The basic idea is that I have two frames, Frame1 and Frame2. Each has one button for launching a dialog, one checkbox, and one exit button. When a dialog is launched from one frame, all inputs to that frame should be blocked, but the other frame should stay unaffected. When the dialog is closed, the first frame also starts getting all inputs.
I am putting the following files below:
- Blocker.java: the class derived from EventQueue. This one basically maintains a vector of restricted components, and assumes that any component in this vector is not supposed to receive any inputs. It is the duty of the various dialogs to add its owner (and contained components) to this vector on show, and remove the owner from the vector on hide/dispose.
- Test2.java: the main; creates two frames, and adds the action listeners etc.
- MyDialog.java: the dialog to be launched on clicking the button in the frame (also supports same dialog launched on clicking button in dialog, as this is also a requirement, but does not currently pertain to my problem).
// Blocker.java
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
public class Blocker extends EventQueue
    private Vector m_oVectRestrictedComponents;
    private EventQueue m_oSystemQ =
            Toolkit.getDefaultToolkit().getSystemEventQueue();
    private static Blocker m_oInstance = null;
    public static synchronized Blocker Instance()
        if(m_oInstance == null)
            m_oInstance = new Blocker();
        return m_oInstance;
    private Blocker()
        m_oVectRestrictedComponents = new Vector();
         m_oSystemQ.push(this);
    public void reset()
         m_oVectRestrictedComponents.removeAllElements();
    public void addRestrictedComponent(final Component oComp)
        if(oComp == null)
             return;
         addChildComponents(oComp);
     public void removeRestrictedComponent(final Component oComp)
          if(oComp == null || m_oVectRestrictedComponents.size() == 0)
               return;
          removeChildComponents(oComp);
      * Add component to list of restricted components. If a JComponent, set its
      * request focus enabled false, and if an abstract button, set its focus
      * painted false. If a container, do the same for all its contained
      * components.
      * @param oComp
    private void addChildComponents(final Component oComp)
        m_oVectRestrictedComponents.add(oComp);
         if(oComp instanceof JComponent)
             ((JComponent)oComp).setRequestFocusEnabled(false);
         if(oComp instanceof AbstractButton)
             ((AbstractButton)oComp).setFocusPainted(false);
        final int iCompCount = ((Container)oComp).getComponentCount();
        if(iCompCount != 0)
            for(int i = 0; i < iCompCount; i++)
                addChildComponents(((Container)oComp).getComponent(i));
      * Remove component from list of restricted components. If a Jcomponent, set
      * its request focus enabled true, and if an abstract button, its set focus
      * painted true. If component is a container, do the same for all its
      * contained components.
      * @param oComp
     private void removeChildComponents(final Component oComp)
         m_oVectRestrictedComponents.remove(oComp);
          if(oComp instanceof JComponent)
              ((JComponent)oComp).setRequestFocusEnabled(true);
          if(oComp instanceof AbstractButton)
              ((AbstractButton)oComp).setFocusPainted(true);
          final int iCompCount = ((Container)oComp).getComponentCount();
          if(iCompCount != 0)
              for(int i = 0; i < iCompCount; i++)
                  removeChildComponents(((Container)oComp).getComponent(i));
    private Component getSource(final AWTEvent event)
        Component source = null;
        // each of these five MouseEvents will still be valid (regardless
        // of their source), so we still want to process them.
        if((event instanceof MouseEvent) &&
                (event.getID() != MouseEvent.MOUSE_DRAGGED) &&
                (event.getID() != MouseEvent.MOUSE_ENTERED) &&
                (event.getID() != MouseEvent.MOUSE_EXITED) &&
                (event.getID() != MouseEvent.MOUSE_MOVED) &&
                (event.getID() != MouseEvent.MOUSE_RELEASED))
            final MouseEvent mouseEvent = (MouseEvent)event;
            source = SwingUtilities.getDeepestComponentAt(
                    mouseEvent.getComponent(),
                    mouseEvent.getX(),
                    mouseEvent.getY());
        else if(event instanceof KeyEvent &&
                event.getSource() instanceof Component)
            source = SwingUtilities.findFocusOwner(
                    (Component)(event.getSource()));
        return source;
    private boolean isSourceBlocked(final Component oSource)
        boolean blocked = false;
        if((m_oVectRestrictedComponents.size() != 0) && (oSource != null))
            final int iNumRestrictedComponents = m_oVectRestrictedComponents.size();
            int i = 0;
            while(i < iNumRestrictedComponents &&
                    (m_oVectRestrictedComponents.get(i).equals(oSource) == false))
                i++;
            blocked = i < iNumRestrictedComponents;
        return blocked;
    protected void dispatchEvent(final AWTEvent event)
         System.out.println();
         System.out.println(event);
         // getSource is a private helper method
         final boolean blocked = isSourceBlocked(getSource(event));
        if(blocked &&
                (event.getID() == MouseEvent.MOUSE_CLICKED ||
                event.getID() == MouseEvent.MOUSE_PRESSED))
            Toolkit.getDefaultToolkit().beep();
        else if(blocked &&
                event instanceof KeyEvent &&
                event.getSource() instanceof Component)
            final DefaultFocusManager dfm = new DefaultFocusManager();
            dfm.getCurrentManager();
            Component currentFocusOwner = getSource(event);
            boolean focusNotFound = true;
            do
                dfm.focusNextComponent(currentFocusOwner);
                currentFocusOwner = SwingUtilities.findFocusOwner(
                        (Component)event.getSource());
                if(currentFocusOwner instanceof JComponent)
                    focusNotFound =
                            (((JComponent)currentFocusOwner).isRequestFocusEnabled() == false);
            while(focusNotFound);
        else
            super.dispatchEvent(event);
// Test2.java
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
* This Test class demonstrates how the Blocker is used.
* The Test opens a new JFrame object containing five different
* components.  The button labeled "Block" will block "Button"
* and "CheckBox".  The button labeled "Unblock" will make "Button"
* and "CheckBox" accessible to the user.
* "Button" and "CheckBox" have no attached functionality.
public class Test2
     private JFrame m_oFrame1;
     private JFrame m_oFrame2;
     private JButton m_oDisplayDialog1;
     private JButton m_oDisplayDialog2;
     public Test2()
          final WindowClosingAdapter oWindowAdapter = new WindowClosingAdapter();
          final DisplayDialogActionListener oDisplayDialogActionListener =
                  new DisplayDialogActionListener();
          final ExitListener oExitListener = new ExitListener();
          m_oFrame1 = new JFrame();
          m_oFrame1.setTitle("Blocker Test1");
          m_oFrame1.addWindowListener(oWindowAdapter);
          m_oFrame1.setSize(400, 200);
          m_oDisplayDialog1 = new JButton("Button1");
          m_oDisplayDialog1.setMnemonic('1');
          m_oDisplayDialog1.addActionListener(oDisplayDialogActionListener);
          final JCheckBox checkBox = new JCheckBox("CheckBox1");
          final JButton exitButton = new JButton("Exit1");
          exitButton.addActionListener(oExitListener);
          Container contentPane = m_oFrame1.getContentPane();
          contentPane.setLayout(new FlowLayout());
          contentPane.add(m_oDisplayDialog1);
          contentPane.add(checkBox);
          contentPane.add(exitButton);
          m_oFrame1.setVisible(true);
          m_oFrame2 = new JFrame();
          m_oFrame2.setTitle("Blocker Test2");
          m_oFrame2.addWindowListener(oWindowAdapter);
          m_oFrame2.setSize(400, 200);
          m_oDisplayDialog2 = new JButton("Button2");
          m_oDisplayDialog2.setMnemonic('2');
          m_oDisplayDialog2.addActionListener(oDisplayDialogActionListener);
          final JCheckBox cb = new JCheckBox("CheckBox2");
          final JButton exitbutton2 = new JButton("Exit2");
          exitbutton2.addActionListener(oExitListener);
          contentPane = m_oFrame2.getContentPane();
          contentPane.setLayout(new FlowLayout());
          contentPane.add(m_oDisplayDialog2);
          contentPane.add(cb);
          contentPane.add(exitbutton2);
          m_oFrame2.setVisible(true);
    public static void main(String[] argv)
         new Test2();
         Blocker.Instance();
     private class DisplayDialogActionListener implements ActionListener
          public void actionPerformed(final ActionEvent e)
               final Object oSource = e.getSource();
               JFrame oParent = null;
               if(oSource.equals(m_oDisplayDialog1))
                    oParent = m_oFrame1;
               else if(oSource.equals(m_oDisplayDialog2))
                    oParent = m_oFrame2;
               if(oParent == null)
                    return;
               final MyDialog oDialog = new MyDialog(oParent);
               oDialog.show();
     private class WindowClosingAdapter extends WindowAdapter
           * Invoked when a window has been closed.
          public void windowClosed(WindowEvent e)
               System.exit(0);
     private class ExitListener implements ActionListener
          public void actionPerformed(final ActionEvent e)
               System.exit(0);
// MyDialog.java
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class MyDialog extends JDialog
     private static int INITIALIZER = 0;
     private final Blocker m_oBlocker = Blocker.Instance();
     public MyDialog(final Frame owner) throws HeadlessException
          super(owner, "Frame Parent" + INITIALIZER);
          INITIALIZER++;
          initializeDialog();
     public MyDialog(final Dialog owner) throws HeadlessException
          super(owner, "Dialog Parent" + INITIALIZER);
          INITIALIZER++;
          initializeDialog();
     private void initializeDialog()
          setSize(200, 100);
          final JButton oDoNothing = new JButton("Do Nothing");
          oDoNothing.addActionListener(new DisplayDialogActionListener());
          final JButton oCloseDialog = new JButton("Close");
          oCloseDialog.addActionListener(new ActionListener()
               public void actionPerformed(final ActionEvent e)
                    MyDialog.this.dispose();
          final Container oContentPane = getContentPane();
          oContentPane.setLayout(new FlowLayout());
          oContentPane.add(oDoNothing);
          oContentPane.add(oCloseDialog);
     public void show()
          System.out.println(getTitle() + " show called");
          super.show();
          System.out.println(getTitle() + " adding owner to restricted list");
          m_oBlocker.addRestrictedComponent(getOwner());
      * Hides the Dialog and then causes show() to return if it is currently
      * blocked.
     public void hide()
          System.out.println(getTitle() + " removing owner from restricted list");
          m_oBlocker.removeRestrictedComponent(getOwner());
          System.out.println(getTitle() + " hide called");
          super.hide();
      * Disposes the Dialog and then causes show() to return if it is currently
      * blocked.
     public void dispose()
          System.out.println(getTitle() + " removing owner from restricted list");
          m_oBlocker.removeRestrictedComponent(getOwner());
          System.out.println(getTitle() + " dispose called");
          super.dispose();
     private class DisplayDialogActionListener implements ActionListener
          public void actionPerformed(final ActionEvent e)
               final MyDialog oDialog = new MyDialog(MyDialog.this);
               oDialog.show();
}Now, my problem is that when i try to display the dialog using a mouse click on the button, there is never any problem, neither does there appear to be a problem if the focus is on the button and I press space/enter. But if there is a mnemonic set, and I use that (like Alt-1), then SOMETIMES, the entire application hangs. I am stumped as to why this is happening... Any help AT ALL is seriously appreciated.
Thanks,
Shefali.