Android custom dialog error Unable to add window-Token null is not for an application

Follow the custom dialog section in the android manual to learn how to use the custom dialog. the following error occurs:

android.view.WindowManager$BadTokenException: Unableto add window--tokennullisnotforan application

The Code logic on the manual is as follows:

Layoutinflater Inflater = (layoutinflater) getapplicationcontext (). getsystemservice (layout_inflater_service );

View layout = Inflater. Inflate (R. layout. custom_dialog,

(Viewgroup) findviewbyid (R. Id. layout_root ));

Textview TV = (textview) layout. findviewbyid (R. Id. custom_text );

TV. settext ("Hello, this is a custom dialfo ");

Imageview IV = (imageview) layout. findviewbyid (R. Id. custom_image );

Iv. setimageresource (R. drawable. Icon );

Builder = new alertdialog. Builder (getapplicationcontext ());

Builder. setview (layout );

Dialog = builder. Create ();

Change the red mark statementBuilder = new alertdialog. Builder (this );

Error cause:

You need to use your activty as the context for the dialog not the application.

Android is looking for a view to display the dialog in and the application does not have one but youractivity will. the application is an object which ties your app together and has a context as it knows about which locale you're re running in and so on,
It relies on activities to display things to the user.