How to check Regular Expression for Timestamp in GWT?

Question

What will be the regular expression for following Timestamp format

YYYY-MM-DD HH:mm:ss.S

YYYY-MM-DD HH:mm:ss.S AM/PM

YYYY-MM-DD HH:mm:ss.S AM/PM Z

YYYY-MM         


        

Answer 1

Just something simple as only describing the pattern like this:

^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2}\.\d{3}(?: [AP]M)?(?: [+-]\d{4})?$

as any tentative of real date validation with a regex sounds inherently wrong.

I got the uppercase Z as RFC822 timezone, regex needs changes to comply to TZDs or general textual time zones.