progressdialog with asynctask

//Al click del pulsante
public void onClick1(View view){

        Log.d("tag","onClick1 è stato aperto");

        new ProgressDialogTask().execute();

 }

//ProgressDialogTask

private class ProgressDialogTask extends AsyncTask<Void, Void, Void>{

        private ProgressDialog dialog;

        ProgressDialogTask(){

            dialog = new ProgressDialog(getBaseContext());


        }

        protected void onPreExecute() {
            dialog.setMax(100);
            dialog.setProgress(0);
            dialog.setTitle("Doing Something");
            dialog.setMessage("Please wait!");
            dialog.setCancelable(false);
            dialog.setIndeterminate(true);

            dialog.show();
        }

        @Override
        protected Void doInBackground(Void... params) {

            while(dialog.getProgress() <= dialog.getMax()){

                try{
                    Thread.sleep(5000);
                }catch(Exception e){

                    e.printStackTrace();
                }

                dialog.incrementProgressBy(5);

            }

            return null;
        }

        @Override
        protected void onPostExecute(Void v){

            dialog.dismiss();
        }



    }