@Override
  public Object getMapValueElement(final Object data, final Object key) {
    if (data == null || key == null) {
      return null;
    }
    if (data instanceof ArrayWritable) {
      final Writable[] mapArray = ((ArrayWritable) data).get();

      if (mapArray == null || mapArray.length == 0) {
        return null;
      }

      for (final Writable obj : mapArray) {
        final ArrayWritable mapObj = (ArrayWritable) obj;
        final Writable[] arr = mapObj.get();
        if (key.equals(arr[0])) {
          return arr[1];
        }
      }
      return null;
    }
    if (data instanceof Map) {
      return ((Map) data).get(key);
    }
    throw new UnsupportedOperationException("Cannot inspect " + data.getClass().getCanonicalName());
  }
The StandardParquetHiveMapInspector will inspect an ArrayWritable, considering it as a Hive map.<br>
It can also inspect a Map if Hive decides to inspect the result of an inspection.
ql/src/java/org/apache/hadoop/hive/ql/io/parquet/serde/StandardParquetHiveMapInspector.java