Question

If map is defined as

private Map<Integer, Integer>   map = new HashMap<Integer, Integer>();

Updating the key works fine as shown below

public void increaseCountInFile(Integer hashCode) {
    if (mapContains(hashCode)) {
        increaseCount(hashCode);
    } else {
        map.put(hashCode, 1);
    }
}

private void increaseCount(Integer fileHashCode) {
    Integer key = map.get(fileHashCode);
    map.remove(fileHashCode);
    map.put(fileHashCode, ++key);
}

private boolean mapContains(Integer fileHashCode) {
    return map.containsKey(fileHashCode);
}

However, i wonder, can the same be done without having to remove the element from the map? (map.remove(fileHashCode);)

++(map.get(fileHashCode)); Looks nice but Java does not like it

Answer 1

You don’t need

map.remove(fileHashCode);

put() will automatically overwrite the entry. You can shorten your increaseCount() method like this:

private void increaseCount(Integer fileHashCode) {
    map.put(fileHashCode, map.get(fileHashCode)+1);
}

Honestly though, I think you’re adding too much abstraction in your code. It really should just be one method unless you have a very good reason otherwise:

public void increaseCountInFile(Integer hashCode) {
    if(map.containsKey(hashCode)) {
        map.put(hashCode, map.get(hashCode)+1);
    } else {
        map.put(hashCode, 1);
    }
}