@Timeout
  public void handletimeout(Timer timer) {
    // delete temp files

    for (File f : deleteTempFileList) {
      dbgLog.fine("file to be deleted: path=" + f.getAbsolutePath() + "\tname=" + f.getName());
      if (f.exists()) {
        boolean sc = f.delete();
        if (!sc) {
          dbgLog.fine(
              "failed to delete file: path=" + f.getAbsolutePath() + "\tname=" + f.getName());
        } else {
          dbgLog.fine("successfully deleted? let's check its existence");
          if (f.exists()) {
            dbgLog.fine("surprise: actually the File still exists");
          } else {
            dbgLog.fine("The file no longer exists");
          }
        }
      }
    }
  }