Validating if given string is a date in Java

Question

I get a string value by a text box in html. I want to validate that string using if condition to see if the given string is a date.

    if (matches ^\d\d\d\d((01|03|05|07|08|10|12)(30|31|[012]\d)|(04|06|09|11)(30|[012]\d)|02[012]\d)$)
    if (endsWith "0229")
         return true or false depending on the year being a leap year
    return true
return false

I fond this code by googling but contain errors and not successful.

Please help me with this matter.

Try parsing the string with a DateFormat and if it throws a parse exception, whell it's not valid input — Raffaele, Aug 27 '15 at 09:54
This would be rather impossible. "01/02/2015" is a date, but so is "February 2nd 2015". There are way to many formats to decently (and trustworthy) do this. — Stultuske, Aug 27 '15 at 09:55

akash · Answer 1 · 2015-08-27T10:01:48.010

I want to validate that string using if condition to see if the given string is a date.

You should better try with parsing.You can use org.apache.commons.lang3.time.DateUtils

For Example :

String[] validFormats = new String[] {"dd.MM.yyyy", "dd.MM/yyyy" };
Date date = DateUtils.parseDate(validFormats);
//Throw ParseException if String is not parsable with given formats

Note here that there is a limitation that it can only parse if date String is in one of the allowed formats. If you don't want to use third party library. You can create your own method and use loop, try to parse one by one if you successfully get date just return date.

sweet clean and simple :) – Jordi Castilla Aug 27 '15 at 10:00 — Jordi Castilla, Aug 27 '15 at 10:00

score 1 · Answer 2 · answered Aug 27 '15 at 10:45

According comments:

your String has some standard or predefined pattern?

yes like 2015-08-30

So, use SimpleDateFormat::parse(String):

Parses text from a string to produce a Date.

class MyDateUtils {
    public static boolean isValidDate(String curDate) {
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        // don't allow dates out of range as 2015-18-33
        format.setLenient(false);  

        Date parsedDate = null;
        try {
            parsedDate = format.parse(curDate);
        } catch (ParseException e) {}

        return parsedDate == null ? false : true;
    }
}

To execute:

MyDateUtils.isValidDate("2015-12-31"); // returns true
MyDateUtils.isValidDate("2015-18-31"); // returns false
MyDateUtils.isValidDate("2015/12/31"); // returns false

Validating if given string is a date in Java

2 Answers2