Null Pointer

[JMacos]

Buongiorno,

Nel mio applet java, quando clicco sull'evento cerca mi da questo errore:

Exception occurred during event dispatching:
java.lang.NullPointerException: null pData
at sun.awt.windows.WComponentPeer._requestFocus(Nativ e Method)
at sun.awt.windows.WComponentPeer.requestFocus(Unknow n Source)
at java.awt.Component.requestFocusHelper(Unknown Source)
at java.awt.Component.requestFocusHelper(Unknown Source)
at java.awt.Component.requestFocus(Unknown Source)
at sun.plugin2.main.client.PluginMain$2.run(Unknown Source)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(U nknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(U nknown Source)
at java.awt.Dialog$1.run(Unknown Source)
at java.awt.Dialog$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.awt.Dialog.show(Unknown Source)
at java.awt.Component.show(Unknown Source)
at java.awt.Component.setVisible(Unknown Source)
at java.awt.Window.setVisible(Unknown Source)
at java.awt.Dialog.setVisible(Unknown Source)
at upload.Upload.actionPerformed(Upload.java:126)
at java.awt.Button.processActionEvent(Unknown Source)
at java.awt.Button.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(U nknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)


nell'evento il codice è:

        if (e.getActionCommand().equals("Cerca")) {

           FileDialog fd = new FileDialog((Frame) null);
            fd.setVisible(true);

            if (fd.getFile() != null) {
                this.directory = fd.getDirectory();
                this.nomeFile = fd.getFile();
                this.pathFile.setText("FILE: " + this.directory + fileSeparator + this.nomeFile);

                uploadFile.setEnabled(true);
                cercaFile.setEnabled(true);
            }
        } 

l'errore viene dato in:
fd.setVisible(true);