code: public void setTimes(String src, long mtime, long atime) throws IOException {
      checkOpen();
      clearFileStatusCache();
  
      try {
        namenode.setTimes(src, mtime, atime);
      } catch(RemoteException re) {
        throw re.unwrapRemoteException(AccessControlException.class,
                                       FileNotFoundException.class);
      }
    }
docs: set the modification and access time of a file
  @throws FileNotFoundException if the path is not a file