public static void main (String [] args) {

        String word = "caramel";
        HashMap<Character, Integer> map = new HashMap<>();

        for (int i = 0; i < word.length(); i++) {

            char ch = word.charAt(i);

            if (map.get(ch) != null) {
                System.out.println("There is a duplicate.");
                System.exit(0);
            }

            map.put(ch, 1);
        }
        System.out.println("There are all unique characters.");
    }