使用java流从HashMap获取特定键

您可以对条目进行流式处理,找到最大值并返回相应的键:

Integer maxKey = 
          map.entrySet()
             .stream() // create a Stream of the entries of the Map
             .max(Comparator.comparingInt(Map.Entry::getValue)) // find Entry with 
                                                                // max value
             .map(Map.Entry::getKey) // get corresponding key of that Entry
             .orElse (null); // return a default value in case the Map is empty