Re: [platform-ui-dev] Problem with JFace PreferenceDialog class

[Bob Foster <bob@xxxxxxxxxx>]

I see you've posted this to both platform-swt-dev and platform-ui-dev. 
Neither is the right place. Please address questions like this to the 
eclipse.platform newsgroup. When you do, it wouldn't hurt to specify 
whether or not you have a standalone application or are writing an 
Eclipse plugin.

Bob Foster

Thilo Brandt wrote:
> Hi together,
>
> I am pretty new to JFace development and I have some trouble with it ;-)
> When calling the following coding twice in my application:
>
> Display display = new Display();
>
> // create a PreferenceManager
> PreferenceManager mgr = new PreferenceManager();
>
> // assign nodes to PreferenceManager
> IPreferenceNode n = new PreferenceNode("page1", new SamplePreferencePage());
> mgr.addToRoot(n);
>
> // create a PreferenceDialog
> PreferenceDialog dlg = new PreferenceDialog(new Shell(display), mgr);
> dlg.setPreferenceStore(new PreferenceStore());
>
> dlg.open();
> display.dispose();
>
> ... I got the following exception:
>
> java.lang.NullPointerException
> 	at
> org.eclipse.jface.preference.PreferenceDialog.createTitleArea(PreferenceDial
> og.java:421)
> 	at
> org.eclipse.jface.preference.PreferenceDialog.createDialogArea(PreferenceDia
> log.java:378)
> 	at org.eclipse.jface.dialogs.Dialog.createContents(Dialog.java:632)
> 	at
> org.eclipse.jface.preference.PreferenceDialog.access$3(PreferenceDialog.java
> :1)
> 	at
> org.eclipse.jface.preference.PreferenceDialog$3.run(PreferenceDialog.java:30
> 7)
> 	at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:69)
> 	at
> org.eclipse.jface.preference.PreferenceDialog.createContents(PreferenceDialo
> g.java:305)
> 	at org.eclipse.jface.window.Window.create(Window.java:348)
> 	at org.eclipse.jface.dialogs.Dialog.create(Dialog.java:925)
> 	at org.eclipse.jface.window.Window.open(Window.java:637)
> 	at
> de.powerisdnmonitor.ui.jface.configuration.ConfigurationCommand.execute(Conf
> igurationCommand.java:47)
>
>
> Is this a bug or do I have to change/add something in my code? I used the
> libraries (jar files) from the Eclispe 3.0.1 build.
> Any hints are appreciated.
>
> BTW, is there a good source with code snippets/examples for JFace developers
> like for
> SWT?
>
> Best regards,
> Thilo