title: null pointer exception during android listview refresh
body: <p>i want to update my list view after downloading complete but it gives me Nullpointer Exception my code is as per under</p>
  
  <pre>
  try {
                      URL url = new URL(GlobalVariable.Getstr());
                      HttpURLConnection c = (HttpURLConnection) url.openConnection();
                      c.setRequestMethod("GET");
                      c.setDoOutput(true);
                      c.connect();
                         int lenghtOfFile = c.getContentLength();
                         Log.d("ANDRO_ASYNC", "Lenght of file: " + lenghtOfFile);
                      String PATH = Environment.getExternalStorageDirectory()
                              + "/download/";
                      Log.v(LOG_TAG, "PATH: " + PATH);
                      File file = new File(PATH);
                      file.mkdirs();
  
                      // String fileName = "workTest.mp3";
                      String fileName = GlobalVariable.Getstrpath().toString();
  
                      File outputFile = new File(file, fileName);
                      FileOutputStream fos = new FileOutputStream(outputFile);
  
                      InputStream is = c.getInputStream();
  
                      byte[] buffer = new byte[1024];
  //                  int len1 = 0;
                       long total = 0;
  //                  while ((len1 = is.read(buffer)) != -1) {
  //                      total += len1;
  //                      publishProgress(""+(int)((total*100)/lenghtOfFile));
  //                      fos.write(buffer, 0, len1);
  //                  
                       while ((count = is.read(buffer)) != -1) {
                              total += count;
                              publishProgress(""+(int)((total*100)/lenghtOfFile));
                              fos.write(buffer, 0, len1);
  
                      }
                      fos.close();
                      is.close();
  //                  ArrayAdapter aa=new ArrayAdapter(FindFilesByType.this, android.R.layout.test_list_item,Ringtones);
  //                  aa.setNotifyOnChange(true);
  //                  lv1.setAdapter(aa);
                      try{
  
                          ((ArrayAdapter) lv1.getAdapter()).notifyDataSetChanged();
  
                  //      adapter.notifyDataSetChanged();
  
  
  
  
                      }
                      catch (Exception e) {
                          Log.i(LOG_TAG, "Error: " + e.toString());
                      }
  
  
  
  </pre>
  
  <p>i am getting the</p>
  
  <p><code>04-28 15:56:17.198: INFO/app(624): Error: java.lang.NullPointerException</code></p>
  
  <p>what is wrong i am doing?</p>
  
  <p>thanks in advance</p>