Java - Write code to walk backward to find if a char within srcString is in validString

Requirements

Write code to walk backward to find if a char within srcString is in validString

Demo

//package com.book2s;

public class Main {
    public static void main(String[] argv) {
        String srcString = "book2s.com";
        String validString = "com";
        System.out.println(lastIndexOfAnyBut(srcString, validString));
    }/*  ww  w.  j  ava2 s. c  o  m*/

    public static int lastIndexOfAnyBut(String srcString, String validString) {
        int result = -1;
        int srcLen = srcString.length();

        // walk backward to find if a char within srcString is in validString
        for (int i = srcLen - 1; i >= 0; i--) {
            // not found, stop it
            if (validString.indexOf(srcString.charAt(i)) == -1) {
                result = i;
                break;
            }

        }

        return result;
    }
}