code: public void saveMonomerCache() throws IOException, MonomerException {
  		File f = new File(NOTATION_DIRECTORY);
  		if (!f.exists()) {
  			f.mkdir();
  		}
  		MonomerCache cache = new MonomerCache();
  		cache.setMonomerDB(getMonomerDB(false));
  		cache.setAttachmentDB(getAttachmentDB());
  		cache.setSmilesMonomerDB(getSmilesMonomerDB(false));
  		serializeMonomerCache(cache, MONOMER_CACHE_FILE_PATH);
  
  		String monomerDbXML = buildMonomerDbXMLFromCache(cache);
  
  		FileOutputStream fos = new FileOutputStream(MONOMER_DB_FILE_PATH);
  		fos.write(monomerDbXML.getBytes());
  		fos.close();
  	}
docs: save monomerCache to disk file
  
  @throws java.io.IOException
  if the monomer can not be saved to disk file
  @throws MonomerException
  if monomer is not valid