reverse string with recursion

class Main {
    public static void main(String[] args) {
        System.out.println(recStringRev("hello",0));
    }
    
    public static String recStringRev(String s, int a) {
        if(a >= s.length()){
            return "";
        }
        char ch = s.charAt(a);
        String rev = recStringRev(s,a+1);
        return rev + ch;
        // reverse loop
        // we can use a stack to reverse
        // here we will try recursion
        
    }
    
    // Public method
    public static int reverse(int n) {
        return reverseHelper(n, 0);
    }

    // Recursive helper function
    private static int reverseHelper(int n, int rev) {
        // Base case
        if (n == 0) return rev;

        int last = n % 10;              // get last digit
        rev = rev * 10 + last;          // append to reversed number

        return reverseHelper(n / 10, rev); // recursive call
    }
}