code: public static String readString(DataInput in) throws IOException {
      int length = readVInt(in);
      if (length == -1) return null;
      byte[] buffer = new byte[length];
      in.readFully(buffer);
      return Text.decode(buffer);
    }
docs: Read a String as a VInt n, followed by n Bytes in Text format.
  
  @param in
  The input stream.
  @return The string
  @throws IOException