#Java Collection HashMap

Question

I want to sort map in descending order by value and print only key having highest value Note: print multiple key if both have same value

 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

what do you mean by "sort a map"? Map in general cannot be arbitrary sorted — Alex Salauyou
– Alex Salauyou, Commented Mar 10, 2016 at 7:10

Eran · Accepted Answer · 2016-03-10 07:00:59Z

1

If you want a secondary ordering according to keys (i.e. if the values are equal, sort be keys in descending order), add a condition for the case of equal values :

    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()));
        }

    });

answered Mar 10, 2016 at 7:00

Eran

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