Positioning dialogs on screen...

[Igor Romanov]

Sometimes you need to display a dialog window on screen, so that it will be center-aligned on parent's window. But how to do this if you have no reference to parent window, for example when overriding actionPerformed() method. Now I doing it like that:
if( e.getSource() instanceof Component )
{
Component comp = (Component) e.getSource();
Frame[] frms = Frame.getFrames();
for( int i=0; i<frms.length; i++ )
{
if( frms[i].isAncestorOf( comp ) )
{
af = frms[i];
break;
}
}
}
Is it ok, or there's a better way?

[Nathan Pruett]

I've always used -

SwingUtilities.getWindowAncestor( (Component)e.getSource() );

[Igor Romanov]

Thanks for a hint!

[Igor Romanov]

It seems, that this will not help if JMenuItem is a source object...

[Nathan Pruett]

The reason it doesn't work is because the getWindowAncestor() method just does a getParent() until it hits a Window or null. The problem is, for MenuItems, a JPopupMenu interrupts the getParent() hierarchy, so getWindowAncestor() hits null. There should probably be either a test for JPopupMenu in the getWindowAncestor() code somewhere to fix this, but you can also use this workaround -

Component source = (Component)e.getSource();
if ( source instanceof JMenuItem ) {
    JMenuItem mi = (JMenuItem)source;
    JPopupMenu pm = (JPopupMenu)mi.getParent();
    source = pm.getInvoker();
}
JFrame w = (JFrame)SwingUtilities.getWindowAncestor( source );