Find The Closest Answer in HashMap

Question

I want to search for a key in a hashmap and find the nearest one to that key!

    HashMap map = new HashMap();
         


        

Answer 1

Iterate over all the keys to find the key with the lowest difference to your target key.

Here's some code that does that:

public static Long nearestKey(Map map, Long target) {
    double minDiff = Double.MAX_VALUE;
    Long nearest = null;
    for (long key : map.keySet()) {
        double diff = Math.abs((double) target - (double) key);
        if (diff < minDiff) {
            nearest = key;
            minDiff = diff;
        }
    }
    return nearest;
}

All that casting to double is to guard against a rollover when target is a large negative and the map key is a large positive