public int get(OpenFileNumStatistics statistics) {
    EnumMap<OpenFileNumStatistics, Integer> statisticsMap = getStatisticMap();
    return statisticsMap.getOrDefault(statistics, UNKNOWN_STATISTICS_ERROR_CODE);
  }
get statistics.

@param statistics get what statistics of open file number
@return open file number
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/utils/OpenFileNumUtil.java