Get error in retrieve pdf file from firebase database

I am trying to retrieve it from firebase

 pdfView= findViewById(R.id.pdfView);      url= String.valueOf(DbQuery.g_paperList.get(DbQuery.g_selected_paper_index).getPaperURL());  }  class RetrievePDFbyte extends AsyncTask<String,Void,byte[]>{           @Override      protected byte [] doInBackground(String... strings) {          InputStream inputStream = null;          try{              URL url=new URL(strings[0]);              HttpsURLConnection httpsURLConnection=(HttpsURLConnection)url.openConnection();              if (httpsURLConnection.getResponseCode()==200){                  inputStream=new BufferedInputStream(httpsURLConnection.getInputStream());              }          }catch (IOException e){              return null;          }          try {              return IOUtils.toByteArray(inputStream);          } catch (IOException e) {              e.printStackTrace();          }          return  null;      }        @Override      protected void onPostExecute(byte[] bytes) {          pdfView.fromBytes(bytes).load();          progress_Dialog.dismiss();      }    }  

but I am not able to use AsyncTask ,doInBackground and onPostExecute. How i acn retrieve it from the firebase database

https://stackoverflow.com/questions/65920661/get-error-in-retrieve-pdf-file-from-firebase-database January 27, 2021 at 09:59PM