#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

• Alex Salauyou: what do you mean by "sort a map"? Map in general cannot be arbitrary sorted

Answer 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()));
 }
 });