Regular Expression for Current Date and Time

Question

I have a Date object (Thu Jul 16 15:54:56 IST 2015).

Date date = new Date();

if(vea.isDateValid("Thu Jul 16 15:04:45 IST 2015","regex")){
    System.out.println("Given Date" + " is a valid date format.");  
} else {  
    System.out.println("Given Date" + " is an invalid date format.");  
}

Please give suggestion for "date" regular Expression without converting to any form.

@anubhava I need to Compare current date and time with Regular Expression.If it matches returns True, else false. — Sai, Jul 16 '15 at 10:32
Why not compare `Date`s directly? Or event `String#equals`? What are you trying to compare? — MadProgrammer, Jul 16 '15 at 10:34
@MadProgrammer I don't need any methods to change date format. just i need "regex" for Current date and time from Date(java.util.Date). — Sai, Jul 16 '15 at 10:39
There A LOT of valid formats for a date (this just 16/07/2015 and Wednesday, 07.16.2015 ). If you don't know the general structure of the String, you can't possibly write a (manageable) single regexp for all the cases — Diego Martinoia, Jul 16 '15 at 10:39
Once you have the defined format, you can instantiate a SimpleDateFormat case with the approriate String, and try to match. If it fails, it's not valid. If it succeeds, it is. — Diego Martinoia, Jul 16 '15 at 10:40
@DiegoMartinoia but those are not valid formats for my requirement. — Sai, Jul 16 '15 at 10:43
Regular Expression will only tell if the "format" is correct, not if the date is valid, which is why people are scratching their heads over your question. Something like [this](http://stackoverflow.com/questions/20231539/java-check-the-date-format-of-current-string-is-according-to-required-format-or/20232680#20232680) will valid a `String` date based on a series of predefined formats, but it will do two things, valid the format AS well as validate the date... — MadProgrammer, Jul 16 '15 at 10:43
@MadProgrammer my question is not about current date. just need format like that only. — Sai, Jul 16 '15 at 10:45
So, would something like `Abc Efg 99 99:99:99 HIJ 9999` be a valid value for your format? Cause that's all regular expression will tell, not if the actual value is valid Date value...just saying ;) — MadProgrammer, Jul 16 '15 at 10:46
^((31(?! (FEB|APR|JUN|SEP|NOV)))|((30|29)(?! FEB))|(29(?= FEB (((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])-(JAN|FEB|MAR|MAY|APR|JUL|JUN|AUG|OCT|SEP|NOV|DEC)-((1[6-9]|[2-9]\d)\d{2})$ — Sai, Jul 16 '15 at 10:50
What is the format you want to parse? Post an example string please. — Diego Martinoia, Jul 16 '15 at 10:54

score 2 · Accepted Answer · answered Jul 16 '15 at 10:58

2

This is the Regex you need :

[A-Z][a-z]{2}\\s[A-Z][a-z]{2}\\s[0-9]{2}\\s[0-9]{2}:[0-9]{2}:[0-9]{2}\\s[A-Z]{3}\\s[0-9]{4}

And in your Java code it would be like this:

Date dt=new Date();
String dateString = dt.toString();

System.out.println(dateString.matches("[A-Z][a-z]{2}\\s[A-Z][a-z]{2}\\s[0-9]{2}\\s[0-9]{2}:[0-9]{2}:[0-9]{2}\\s[A-Z]{3}\\s[0-9]{4}"));

Here's the Working DEMO.

answered Jul 16 '15 at 10:58

cнŝdk

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Thank you work like charm!!!! – Sai Jul 16 '15 at 11:40
@paanipuri You are welcome, glad it helps, – cнŝdk Jul 16 '15 at 11:50

score 0 · Answer 2 · answered Jul 16 '15 at 11:42

Something like this should also work, i think it is more convenient to read the format this way:

    SimpleDateFormat sdf = new SimpleDateFormat("EEE MMM dd hh:mm:ss z YYYY);

    try {
        Date date = sdf.parse(dateToValidate);
    } catch (ParseException e) {
        return false;
    }
    return true;

Regular Expression for Current Date and Time

2 Answers2