Reverse with recursion

Back.java

public class Back {
    
    public static void main(String[] args) {
        System.out.println(backRec("cs-111"));
    }
    
    static String back(String x) {
        String y = "";
        for (int i=0; i<x.length(); i++) {
            y = y + x.charAt(x.length()-1-i);
        }
        return y;
    }
    
    static String backRec(String x) {
        if (x.length() > 0) {
            return x.charAt(x.length()-1) + backRec(x.substring(0, x.length()-1));
        }
        else {
            return "";
        }
    }
}