public static String convertToString(byte[] bytes, int start, int length) {
    try {
      return Text.decode(bytes, start, length);
    } catch (CharacterCodingException e) {
      return null;
    }
  }
Convert a UTF-8 byte array to String.

@param bytes
         The byte[] containing the UTF-8 String.
@param start
         The start position inside the bytes.
@param length
         The length of the data, starting from "start"
@return The unicode String
serde/src/java/org/apache/hadoop/hive/serde2/lazy/LazyUtils.java