Unable to add window--token null was not for an application

The following error occurred in the code:

android.view.windowmanager$badtokenexception:unable to add window--token null was not for an application

Analysis:

The problem is new Alertdialog.builder (context), although the parameter here is Alertdialog.builder (context context)

However, we cannot use the context obtained by Getapplicationcontext () and must use the activity's context object because there is only one activity to add a form.  

Workaround:

Use the activity's Context object for the parameters in the new Alertdialog.builder (context context)

Popup Confirmation Box

New Alertdialog.builder (Mainactivity.this). Settitle (R.string.confirm_title). Setmessage (R.string.confirm_content ). Setpositivebutton (R.STRING.CONFIRM_OK, New Onclicklistener () {@Overridepublic void OnClick (dialoginterface dialoginterface, int arg1) {Dialoginterface.dismiss (); Masterclear (Getapplicationcontext ());}}). Setnegativebutton (R.string.confirm_cancel, New Onclicklistener () {@Overridepublic void OnClick (dialoginterface dialoginterface, int arg1) {dialoginterface.cancel ();}}). Show ();

Unable to add window--token null was not for an application