validate-date-using-regex.java

private static final String IS_DATE_MONTH_YEAR_FORMAT_PATTERN = "^(?:(?:31([/\\-.])(?:0?[13578]|1[02]))\\1|" +
            "(?:(?:29|30)([/\\-.])(?:0?[13-9]|1[0-2])\\2))(?:(?:1[6-9]|[2-9]\\d)?\\d{2})$|" +
            "^(?:29([/\\-.])0?2\\3(?:(?:1[6-9]|[2-9]\\d)?(?:0[48]|[2468][048]|[13579][26])|(?:(?:16|[2468][048]|[3579][26])00)))$|" +
            "^(?:0?[1-9]|1\\d|2[0-8])([/\\-.])(?:(?:0?[1-9])|(?:1[0-2]))\\4(?:(?:1[6-9]|[2-9]\\d)?\\d{2})$";

    private static final String IS_MONTH_DATE_YEAR_FORMAT_PATTERN = "^(?:(?:(?:0?[13578]|1[02])([/\\-.])31)\\1|" +
            "(?:(?:0?[13-9]|1[0-2])([/\\-.])(?:29|30)\\2))(?:(?:1[6-9]|[2-9]\\d)?\\d{2})$|" +
            "^(?:0?2([/\\-.])29\\3(?:(?:1[6-9]|[2-9]\\d)?(?:0[48]|[2468][048]|[13579][26])|(?:(?:16|[2468][048]|[3579][26])00)))$|" +
            "^(?:(?:0?[1-9])|(?:1[0-2]))([/\\-.])(?:0?[1-9]|1\\d|2[0-8])\\4(?:(?:1[6-9]|[2-9]\\d)?\\d{2})$";