private void writeToFile(String data, boolean append) {
    data = Settings.getMacAddress() + "\n" + data;

    File rootPath = Environment.getExternalStorageDirectory();
    File statsDir;
    statsDir = new File(rootPath + "/BU-Stat-Collector/");

    if (!statsDir.exists()) statsDir.mkdirs();

    try {
      File file = new File(Settings.getHashFilePath());
      FileOutputStream fos = new FileOutputStream(file, append);
      fos.write(data.getBytes());
      fos.close();
    } catch (Exception e) {
      Log.d(Settings.TAG, "Unable to write hash info in file. Details:\n" + e.toString());
    }
  }