code: public void put(String keyStr, String valueStr) throws DatabaseException {
  		DatabaseEntry key = new DatabaseEntry(stringToBytes(keyStr));
  		DatabaseEntry data = new DatabaseEntry(stringToBytes(valueStr));
  		db.put(null, key, data);            
  	}
docs: persistantly store key-value pair
  @param keyStr
  @param valueStr
  @throws DatabaseException