1190. Reverse substrings between each pair of parentheses

//1190. Reverse substrings between each pair of parentheses

class Solution {
    int i = 0;

    public String reverseParentheses(String s) {
        char[] ar = s.toCharArray();
        return func(ar);
    }

    public String func(char[] s) {
        StringBuilder sb = new StringBuilder();

        while(i < s.length){
            if(s[i] == ')'){
                i++;
                return sb.reverse().toString();
            }else if(s[i] == '('){
                i++;
                String st  = func(s);
                sb.append(st);
            }else{
                sb.append(s[i]);
                i++;
            }
        }
        return sb.toString();
    }
}