public static void main (String args[]) {
        Map<String, String> map = new HashMap();

        fillData(map);

        String[] strings = keysAsArray(map);
        for (String string : strings) {
            System.out.println(string);
        }
        System.out.println("");
        List<String> list = keysAsList(map);
        for (String string : list) {
            System.out.println(string);
        }
    }