code: public String getString(String fieldName, Charset charset) throws DbfException {
          Object value = get(fieldName);
          return value == null
                  ? null
                  : new String(trimLeftSpaces((byte[]) value), charset);
      }
docs: Retrieves the value of the designated field as String
  using given charset.
  
  @param fieldName the name of the field
  @param charset the charset to be used to decode field value
  @return the field value, or null (if the dbf value is NULL)
  @throws DbfException if there's no field with name fieldName