Focus in a JPopupMenu

[Jeff SmithX]

Hi, I'm having quite a bit of trouble getting the focus into a popup menu. Here's what I'm doing:

• I created a JPopupMenu and added a JList as it's only component.
  
• I created a JButton that when clicked on displays the popup menu.
  

What I want is for the popup menu to be displayed and the JList in the menu to have focus so the user can immediately just press the up and down arrows to go up and down through the items. The problem is that it doesn't have the focus. Instead you have to click once in the JList, then you can start moving up and down with the up and down arrows.
I've tried everything I can think of. Calling list.requestFocus() in the button's actionEvent after the menu has been shown causes a NullPointerException and calling list.requestDefaultFocus() after the menu has been shown doesn't cause errors, but doesn't actually give the list focus.
Here's my code, maybe you can tell me what I'm doing wrong (this is all just inside a main method in my test class):


JFrame window = new JFrame();

final JPopupMenu menu = new JPopupMenu();
// some test data for the list
Vector data = new Vector();
data.add( "test data 01" );
data.add( "test data 02" );
data.add( "test data 03" );
data.add( "test data 04" );
data.add( "test data 05" );
data.add( "test data 06" );
data.add( "test data 07" );
data.add( "test data 08" );
data.add( "test data 09" );
data.add( "test data 10" );
data.add( "test data 11" );
data.add( "test data 12" );

final JList list = new JList( data );

// just so the list looks a little nicer
list.setBorder( BorderFactory.createEmptyBorder( 0, 1, 0, 1 ) );

// Listen for "Enter" to be pressed
list.addKeyListener( new KeyAdapter() {
   public void keyTyped( KeyEvent e ) {
      if ( e.getKeyChar() == KeyEvent.VK_ENTER ) {
         // Print selected item and hide menu
         System.out.println( list.getSelectedValue() );
         menu.setVisible( false );
      }
   }
});

// Listen for a double mouse click
list.addMouseListener( new MouseAdapter() {
   public void mouseClicked( MouseEvent e ) {
      if ( e.getClickCount() > 1 ) {
         // Print selected item and hide menu
         System.out.println( list.getSelectedValue() );
         menu.setVisible( false );
      }
   }
});

// Scroll Pane for the list
final JScrollPane scroller = new JScrollPane( list );

menu.add( scroller );

// Button to show the menu
final JButton button = new JButton( "show" );
button.addActionListener( new ActionListener() {
   public void actionPerformed( ActionEvent e ) {
      menu.show( button, 0, 0 );
      // transfer focus to list -- DOESN'T WORK!!!!!
      // list.requestFocus() <-- causes errors on second display
      //                         of popup menu.
      list.requestDefaultFocus();
   }
});

// Add everything, and a few other dummy buttons.
window.getContentPane().setLayout( new BorderLayout() );
window.getContentPane().add( button, BorderLayout.NORTH );
window.getContentPane().add( new JButton( "dummy1" ), BorderLayout.CENTER );
window.getContentPane().add( new JButton( "dummy2" ), BorderLayout.SOUTH );

window.pack();
window.setVisible( true );

window.addWindowListener( new WindowAdapter() {
   public void windowClosing( WindowEvent e ) {
      System.exit( 0 );
   }
});

[Jagan Reddy]

Hi Jeff,

Instead of using list.requestDefaultFocus() use

menu.requestDefaultFocus(). I tried out and is working ..
Regards,
Jagan Reddy.

[Jeff SmithX]

Thanks, I thought I'd tried everything, but apparently I hadn't... that worked great. :-)
Jeff

[Jeff SmithX]

Ok, this is very odd. The first time I ran it with that code everything worked fine, but now it's not??? After I closed the program, and ran it again the menu didn't have focus. And then, without closing the program (just the menu), I clicked the button again to get the menu up, and whenever the mouse is moved within the bounds of the menu, NullPointerException's are thrown until the list recieves focus by actually clicking in it? Do you experience this same problem, or is it just me?
Thanks,
Jeff