code: public static int indexOfAny(String str, char[] searchChars) {
        if (isEmpty(str) || searchChars == null) {
            return -1;
        }
        for (int i = 0; i < str.length(); i++) {
            char ch = str.charAt(i);
            for (int j = 0; j < searchChars.length; j++) {
                if (searchChars[j] == ch) {
                    return i;
                }
            }
        }
        return -1;
    }
docs: <p>Search a String to find the first index of any
  character in the given set of characters.</p>
  
  <p>A <code>null</code> String will return <code>-1</code>.
  A <code>null</code> or zero length search array will return <code>-1</code>.</p>
  
  <pre>
  GosuStringUtil.indexOfAny(null, *)                = -1
  GosuStringUtil.indexOfAny("", *)                  = -1
  GosuStringUtil.indexOfAny(*, null)                = -1
  GosuStringUtil.indexOfAny(*, [])                  = -1
  GosuStringUtil.indexOfAny("zzabyycdxx",['z','a']) = 0
  GosuStringUtil.indexOfAny("zzabyycdxx",['b','y']) = 3
  GosuStringUtil.indexOfAny("aba", ['z'])           = -1
  </pre>
  
  @param str  the String to check, may be null
  @param searchChars  the chars to search for, may be null
  @return the index of any of the chars, -1 if no match or null input
  @since 2.0