code: public synchronized boolean sync() {
  		if (!validState) {
  			throw new InvalidStateException();
  		}
  		try {
  			fc.force(false);
  			return true;
  		} catch (Exception e) {
  			log.error("Exception in sync()", e);
  		}
  		return false;
  	}
docs: Forces any updates to this file to be written to the storage device that contains it.
  
  @return false if exception occur