FULL PRODUCT VERSION :
java version "1.6.0-beta2"
Java(TM) SE Runtime Environment (build 1.6.0-beta2-b79)
Java HotSpot(TM) Client VM (build 1.6.0-beta2-b79, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP 5.1.26000: Service Pack 2


A DESCRIPTION OF THE PROBLEM :
Regression: java.awt.FileDialog.setVisible(true) throws an exception

REGRESSION. Last worked in version mustang, 1.5.0

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :

It worked with Mustang early access build b75.
Run example code attached below

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
No exception

ERROR MESSAGES/STACK TRACES THAT OCCUR :
Exception in thread "main" java.lang.NullPointerException: null pData
        at sun.awt.windows.WWindowPeer.setFocusableWindow(Native Method)
        at sun.awt.windows.WWindowPeer.updateFocusableWindowState(WWindowPeer.java:6
        at java.awt.Window.updateChildFocusableWindowState(Window.java:751)
        at java.awt.Dialog.conditionalShow(Dialog.java:925)
        at java.awt.Dialog.show(Dialog.java:1028)
        at java.awt.Component.show(Component.java:1415)
        at java.awt.Component.setVisible(Component.java:1368)
        at java.awt.Window.setVisible(Window.java:694)
        at java.awt.Dialog.setVisible(Dialog.java:979)
        at OpenDialogRegression.openNativeFileDialog(OpenDialogRegression.java:15)
        at OpenDialogRegression.main(OpenDialogRegression.java:30)

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------

import java.awt.*;
import java.awt.event.*;
import java.io.File;
import java.io.FilenameFilter;
import java.net.URL;
import javax.swing.*;

public class OpenDialogRegression
{
   public static File[] openNativeFileDialog (Frame main_frame)
    {
        FileDialog fd = new FileDialog (main_frame, "hi");

        fd.setVisible (true);

        String name = fd.getFile ();
        if ( name == null )
            return null;

        String dir = fd.getDirectory ();
        if ( dir != null )
            name = dir + name;

        return new File[] { new File (name) };
    }

    public static void main(String args[])
    {
openNativeFileDialog (new JFrame() );
    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
JFileChooser. I use native FileDialog in order to control files and dirs, like delete, rename etc.

Release Regression From : 5.0
The above release value was the last known release where this
bug was known to work. Since then there has been a regression.