Question

I have an assignment, This is my HashMap initialization.. I can only use standard JAVA API.

private static HashMap<String, HashSet<String>> hMap = new HashMap<String, HashSet<String>>();

Is it possible to get the Key of a specified value say getkey(hMap,”today”) and it would return the key where today is located..

Aslo is there a way to get the last value of a Key in my HashSet?

Any help is appreciated thanks!

Answer 1

But actually you can have more than one keys which has “today”. So I return List.toString with keys

private static HashMap<String, HashSet<String>> hMap = new HashMap<String, HashSet<String>>();

public static String getKey(Map<String, HashSet<String>> map, String value) {
    List<String> returnKey = new ArrayList<String>();

    for (String s : map.keySet()) {
        if (map.get(s).contains(value)) {
            returnKey.add(s);
        }
    }

    return returnKey.toString();

}

public static void main(String[] args) {
    // put sth to hMap
    System.out.println(getKey(hMap, "today"));
}