Query features from ArcGIS Feature Layer in Android

QueryFeatureLayer.java

  /*
   * Query features from the feature layer
   */
  private void queryFeatureLayer(){
    // create a Query
    Query query = new Query();
    // set spatial reference 
    SpatialReference sr = SpatialReference.create(102100);
    // set the geometry to the sketch polygon
    query.setGeometry(selection);
    // query features that are completely contained by selection
    query.setSpatialRelationship(SpatialRelationship.CONTAINS);
    // set query in/out spatial ref
    query.setInSpatialReference(sr);
    query.setOutSpatialReference(sr);
    // return all features
    query.setOutFields(new String[]{"*"});
    // include geometry in result set
    query.setReturnGeometry(true);
    // run query on FeatureLayer off UI thread
    featureLayer.queryFeatures(query, new CallbackListener<FeatureSet>() {

      // an error occurred, log exception
      @Override
      public void onError(Throwable e) {
        Log.e("Test", "Unable to perform query", e);
      }

      // create json from resulting FeatureSet
      @Override
      public void onCallback(FeatureSet result) {
        if(result != null){
          FileOutputStream outstream = null;
          try {
            // create feature set as json string
            String fsstring = FeatureSet.toJson(result);
            // create fully qualified path for json file
            path = createJsonFile();
            // create a File from json fully qualified path
            File outfile = new File(path);
            // create output stream to write to json file
            outstream = new FileOutputStream(outfile);
            outstream.write(fsstring.getBytes());
            // close output stream
            outstream.close();
            // create new Runnable to be added to message queue
            handler.post(new MyRunnable());
          } catch (Exception e) {
            e.printStackTrace();
            if(outstream!=null){
              try {
                outstream.close();
                handler.post(new MyRunnable());
              } catch (IOException e1) {
                e1.printStackTrace();
              }
            }
          }

        }
      }});
  }

  /*
   * Create the json file location and name
   * structure
   */
  public String createJsonFile(){
    StringBuilder sb = new StringBuilder();
    sb.append(demoDataFile.getAbsolutePath());
    sb.append(File.separator);
    sb.append(offlineDataSDCardDirName);
    sb.append(File.separator);
    sb.append(filename);
    sb.append(OFFLINE_FILE_EXTENSION);
    return sb.toString();
  }