如何计算具有相同键的不同哈希图的值之和？

Question

So I have this hashmap named "hm" which produces the following output(NOTE: this is just a selection) :

{1=35, 2=52, 3=61, 4=68, 5=68, 6=70, 7=70, 8=70, 9=70, 10=72, 11=72}

{1=35, 2=52, 3=61, 4=68, 5=70, 6=70, 7=70, 8=68, 9=72, 10=72, 11=72}

{1=35, 2=52, 3=61, 4=68, 5=68, 6=70, 7=70, 8=70, 9=72, 10=72, 11=72}

This output was created with the following code(NOTE : the rest of the class code is not shown here) :

private int scores;
HashMap<Integer,Integer> hm = new HashMap<>();

for (int i = 0; i < fileLines.length(); i++) {
    char character = fileLines.charAt(i);
    this.scores = character;
    int position = i +1;
    hm.put(position,this.scores);
 }
 System.out.println(hm);

What I am trying to do is put all these hashmaps together into one hashmap with as value the sum of the values per key. I am familiar with Python's defaultdict, but could not find an equivalent working example. I have searched for an answer and hit those answers below but they do not solve my problem.

How to calculate a value for each key of a HashMap?

what java collection that provides multiple values for the same key

is there a Java equivalent of Python's defaultdict?

The desired output would be :

{1=105, 2=156, 3=183 , 4=204 ,5=206 ..... and so on}

Eventually the average per position(key) has to be calculated but that is a problem I think I can fix on my own when I know how to do the above.

EDIT : The real output is much much bigger ! Think about 100+ of the hashmaps with more than 100 keys.

Answer 1

Try with something like that

public Map<Integer, Integer> combine(List<Map<Integer, Integer>> maps) {
    Map<Integer, Integer> result = new HashMap<Integer, Integer>();
    for (Map<Integer, Integer> map : maps) {
        for (Map.Entry<Integer, Integer> entry : map.entrySet()) {
            int newValue = entry.getValue();
            Integer existingValue = result.get(entry.getKey());
            if (existingValue != null) {
                 newValue = newValue + existingValue;
            }
            result.put(entry.getKey(),  newValue);
        }
    }
    return result;
}

Basically:

• Create a new map for the result
• Iterate over each map
• Take each element and if already present in the result increment the value, if not put it in the map
• return the result

Answer 2

   newHashMap.put(key1,map1.get(key1)+map2.get(key1)+map3.get(key1));