Java Map util method to deep check for containKey?

Question

Does anybody know a Util library which contains something like a Util.deepContains() method? I have to check a map and it's nested entries for a key. I surely can write my own logic but I like to use Utils to keep my code a bit cleaner and save some unit tests.

The map structure is Map<String, Map<String, Object>> where Object can be another Map and so on.

Answer 1

NO, I am not aware of any existing function in a library. However, if there exist any, is it worth to import the whole library because of one use-case only? Feel free to create your own function. Consider the following example map structure:

{
    map2={
        map3={
            4=4, 
            5=5
        }
    }, 
    map4={
        6=6, 
        7=7
    }
}

Regardless how many Map<String, Object> are nested, the following recursive function iterates all the values until it finds the correct one. During the comparison, you have to cast from Object to T due to the correct comparison.

static <T> boolean deepContains(Map<?, ?> map, T item) {
    for (Entry<?, ?> entry: map.entrySet()) {
        final Object value = entry.getValue();
        boolean returned = false;
        if (value instanceof Map<?, ?>) {
            returned = deepContains((Map<?, ?>) value, item);
        } else {
            returned = item.getClass().cast(value).equals(item);
        }
        if (returned) {return true;}
    }
    return false;
}

Usage:

boolean result = deepContains(map, "4"); // returns true
boolean result = deepContains(map, "7"); // returns true
boolean result = deepContains(map, "8"); // returns false