Java – How to find the keys associated with the maximum value in HashMap

data structureshashmapindexingjava

I want to find the keys associated with the maximum value in a HashMap<Integer,Integer>.

I have seen the question Finding Key associated with max Value in a Java Map, but there are certain restrictions while using HashMap.

Any help would be appreciated.

Best Answer

What you can do here is just sort your HashMap and pick the first or last keys to get max or min values.

public LinkedHashMap<Integer,Integer> sortHashMapByValues(HashMap<Integer,Integer> passedMap) {
   List<Integer> mapKeys = new ArrayList<Integer>(passedMap.keySet());
   List<Integer> mapValues = new ArrayList<Integer>(passedMap.values());
   Collections.sort(mapValues);
   Collections.sort(mapKeys);

   LinkedHashMap<Integer,Integer> sortedMap = 
       new LinkedHashMap<Integer,Integer>();

   Iterator valueIt = mapValues.iterator();
   while (valueIt.hasNext()) {
       Object val = valueIt.next();
    Iterator keyIt = mapKeys.iterator();

    while (keyIt.hasNext()) {
        int key = (Integer)keyIt.next();
        int comp1 = (Integer)passedMap.get(key);
        int comp2 = (Integer)val;

        if (comp1 == comp2){
            passedMap.remove(key);
            mapKeys.remove(key);
            sortedMap.put(key,(Integer) val);
            break;
        }

    }

}
return sortedMap;
}

Remember -Their may be more then one keys with same value.

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