* @return true if the email-address is correct, false otherwise
     */
    public static boolean checkEmail(String str) {
        int i;
        boolean atChar = false;
        if (!str.contains(".")) {
            return false;
        }
        for (i = 0; i < str.length(); i++) {
            if (str.charAt(i) == '@') {
                if (atChar) {
                    return false;
                } else {
                    atChar = true;
                }
            }
        }
        if (atChar) {
            return true;
        } else {
            return false;
        }
    }