public static void main(String[] args) {

        String str = "04e1";

        String myStr[] = { "a", "b", "c", "d", "e", "f" };

        int result = 0;

        int n = 1;

        for (int i = str.length() - 1; i >= 0; i--) {

            String param = str.substring(i, i + 1);

            for (int j = 0; j < myStr.length; j++) {

                if (param.equalsIgnoreCase(myStr[j])) {

                    param = "1" + String.valueOf(j);

                }

            }

            result += Integer.parseInt(param) * n;

            n *= 16;

        }

        System.out.println(result);

        System.out.println(Integer.parseInt(str, 16));

    }