Android Back Button and Progress Dialog

Question

I have an AsyncTask that shows a progressDialog whilst working (it calls runOnUiThread from within doInBackground to show the progress dialog).

Whilst its running I want to allow the use of the back button to cancel the operation; someone else has had this problem: BACK Button is not working ,while progressDialog is running

For what ever reason I can't reply to that thread, hence having to start another?! (Another question for another day)

I had the same idea as Sandy but this code is never called whilst the progressDialog is showing, why is this? I have implemented it inside my main activity class, does the progressDialog take the foreground focus away from my class temporarily?

Answer 1

First, you should show your dialog from OnPreExecute, hide it in OnPostExecute, and - if necessary - modify it by publishing progress. (see here)

Now to your question: ProgressDialog.show() can take a OnCancelListener as an argument. You should provide one that calls cancel() on the progress dialog instance.

example:

    @Override     protected void onPreExecute(){         _progressDialog = ProgressDialog.show(                 YourActivity.this,                 "Title",                 "Message",                 true,                 true,                 new DialogInterface.OnCancelListener(){                     @Override                     public void onCancel(DialogInterface dialog) {                         YourTask.this.cancel(true);                         finish();                     }                 }         );     } 

where _progressDialog is a ProgressDialog member of YourTask.

This class was deprecated in API level 26. ProgressDialog is a modal dialog, which prevents the user from interacting with the app. Instead of using this class, you should use a progress indicator like ProgressBar, which can be embedded in your app's UI. Alternatively, you can use a notification to inform the user of the task's progress. LINK

Answer 2

This can be achieved by the following code fragment:

progress.setCancelable(true); progress.setCanceledOnTouchOutside(false); 

progress is the ProgressDialog object...

This will enable the back button to close the dialog but prevent any touch input to do that...