code: public static int findFirstOf(String string, String chars, int start, int end) {
          for (int i = start; i < end; i++) {
              char c = string.charAt(i);
              if (chars.indexOf(c) != -1) {
                  return i;
              }
          }
          return end;
      }
docs: Returns the index of the first char of {@code chars} in {@code string}
  bounded between {@code start} and {@code end}. This returns {@code end}
  if none of the characters exist in the requested range.