super reduced string

   // Complete the superReducedString function below.
    static String superReducedString(String s) {
        char c = s.charAt(0);
        int i = 0;
        Stack<Character> stack = new Stack<>();
        while (i < s.length()) {
            c = s.charAt(i);
            if (!stack.empty() && stack.peek() == s.charAt(i)) {
                stack.pop();
            } else {
                stack.push(s.charAt(i));
            }
            ++i;
        }
        if (stack.empty()) {
            return "Empty String";
        } else {
            StringBuilder sb = new StringBuilder();
            for (Character ch : stack) {
                sb.append(ch);
            }
            return sb.toString();
        }


    }