#Java集合HashMap

Question

我希望按值按降序排列映射，并仅打印具有最高值的键注意:如果两个键具有相同的值，则打印多个键

 map.put(5,3);
    map.put(4,1);
    map.put(2,2);
    map.put(10,3);



     Set <Map.Entry<Integer,Integer>>set = map.entrySet();
        List <Map.Entry<Integer,Integer>> list = new ArrayList<Map.Entry<Integer,Integer>>(set);

        Collections.sort(list, new Comparator<Map.Entry<Integer,Integer>>(){
            public int compare(Map.Entry<Integer,Integer> obj1, Map.Entry<Integer,Integer> obj2){
                return (obj2.getValue().compareTo(obj1.getValue()));
            }

        });

Now i got output 5,10 but i want output as 10,5

Answer 1

如果您希望根据键进行二次排序(即，如果值相等，则按降序排序be键)，则为值相等的情况添加一个条件：

    Collections.sort(list, new Comparator<Map.Entry<Integer,Integer>>(){
        public int compare(Map.Entry<Integer,Integer> obj1, Map.Entry<Integer,Integer> obj2){
            if (!obj2.getValue().equals(obj1.getValue()))
                return (obj2.getValue().compareTo(obj1.getValue()));
            else
                return (obj2.getKey().compareTo(obj1.getKey()));
        }

    });