code: public void put(String keyStr, String valueStr) {
          try {
              DatabaseEntry key = new DatabaseEntry(keyStr.getBytes("UTF-8"));
              DatabaseEntry data = new DatabaseEntry(valueStr.getBytes("UTF-8"));
              db.put(null, key, data);            
           } catch (DatabaseException e) {
               e.printStackTrace();
           } catch (UnsupportedEncodingException e) {
              e.printStackTrace();
          }
      }
docs: persistantly store key-value pair
  @param keyStr
  @param valueStr