code: public synchronized void close() throws SecurityException {
          super.close();
          // Unlock any lock file.
          if (lockFileName == null) {
              return;
          }
          try {
              // Closing the lock file's FileOutputStream will close
              // the underlying channel and free any locks.
              lockStream.close();
          } catch (Exception ex) {
              // Problems closing the stream.  Punt.
          }
          synchronized(locks) {
              locks.remove(lockFileName);
          }
          new File(lockFileName).delete();
          lockFileName = null;
          lockStream = null;
      }
docs: Close all the files.
  
  @exception  SecurityException  if a security manager exists and if
  the caller does not have <tt>LoggingPermission("control")</tt>.