private boolean compareColumnVector(ColumnVector cv1, ColumnVector cv2) {
    if (cv1 == null && cv2 == null) {
      return true;
    } else {
      if (cv1 != null && cv2 != null) {
        if (cv1 instanceof LongColumnVector && cv2 instanceof LongColumnVector) {
          return compareLongColumnVector((LongColumnVector) cv1, (LongColumnVector) cv2);
        }
        if (cv1 instanceof DoubleColumnVector && cv2 instanceof DoubleColumnVector) {
          return compareDoubleColumnVector((DoubleColumnVector) cv1, (DoubleColumnVector) cv2);
        }
        if (cv1 instanceof BytesColumnVector && cv2 instanceof BytesColumnVector) {
          return compareBytesColumnVector((BytesColumnVector) cv1, (BytesColumnVector) cv2);
        }
        if (cv1 instanceof DecimalColumnVector && cv2 instanceof DecimalColumnVector) {
          return compareDecimalColumnVector((DecimalColumnVector) cv1, (DecimalColumnVector) cv2);
        }
        throw new RuntimeException(
            "Unsupported ColumnVector comparision between " + cv1.getClass().getName()
                + " and " + cv2.getClass().getName());
      } else {
        return false;
      }
    }
  }
Get the child ColumnVector of ListColumnVector
ql/src/java/org/apache/hadoop/hive/ql/io/parquet/vector/VectorizedListColumnReader.java