how to merge more than one hashmaps also sum the values of same key in java

Question

ı am trying to merge more than one hashmaps also sum the values of same key, ı want to explain my problem with toy example as follows

    HashMap

        

Answer 1

ı improve Lucas Ross's code. in stead of enter map by one by in function ı give all maps one times to function with arraylist of hashmap like that

    public HashMap mergeAndAdd(ArrayList> maplist) {
    HashMap result = new HashMap<>();
    for (HashMap map : maplist) {
        for (Map.Entry entry : map.entrySet()) {
            String key = entry.getKey();
            Integer current = result.get(key);
            result.put(key, current == null ? entry.getValue() : entry.getValue() + current);
        }
    }
    return result;
}

}

it works too. thanks to everbody