/**
   * Creates a singleton DataLogger or returns the already created object. Before writing to a file
   * first openWriter() must be called.
   *
   * @return The singleton object.
   */
  public static DataLogger getInstance() {
    if (singletonInstance == null) {
      singletonInstance = new DataLogger();

      singletonInstance.mFileName = "ProbeLog_" + new Date().getTime();
      singletonInstance.openWriter();
    }
    return singletonInstance;
  }