@Override
  public String readString() throws TException {
    String ret;
    if (!inner) {
      ret = columns != null && index < columns.length ? columns[index] : null;
      index++;
    } else {
      ret = fields != null && innerIndex < fields.length ? fields[innerIndex]
          : null;
      innerIndex++;
    }
    if (ret == null || ret.equals(nullString)) {
      return returnNulls ? null : "";
    } else {
      return ret;
    }
  }
Skip past the current field Just increments the field index counter.
serde/src/java/org/apache/hadoop/hive/serde2/thrift/TCTLSeparatedProtocol.java