code: private void forceClose() {
      if (file != null) {
        if (file.exists() && file.canWrite() && !file.delete()) {
          log.debug("couldn't delete " + file.getName());
        }
        file = null;
      }
      try {
        objectInputStream.close();
      } catch (IOException e) {
        log.debug(e);
      }
      closed = true;
    }
docs: Force close.