How to Convert A Clojure/Java Date to Simpler Form

Question

I want to take

(str (Date.))
\"Thu Feb 07 12:15:03 EST 2013\"

and turn it into a string, so it can be input into an Informix date field mm

Answer 1

(def date (java.util.Date.))
date 
=> #inst "2013-02-07T19:08:12.107-00:00"

You can directly format to desired format

(.format (java.text.SimpleDateFormat. "MM/dd/yyyy") date)
=> "02/07/2013"

But if starting from a string,

(str date)
=> "Thu Feb 07 13:08:12 CST 2013"

you must first parse using that string's format

(def df (java.text.SimpleDateFormat. "EEE MMM d HH:mm:ss zzz yyyy"))
(.parse df (str date))
=> #inst "2013-02-07T19:08:12.107-00:00"

and then back to the desired format

(.format (java.text.SimpleDateFormat. "MM/dd/yyyy") (.parse df (str date)))
=> "02/07/2013"

You might also want to look into some time and date libraries: What are the Clojure time and date libraries?.

Answer 2

.parse takes a string in the format specified in the SimpleDateFormat constructor and turns it into a Date object. If you can just pass in the date, then use .format passing it the date to be formatted. If you need to pass in a string, then you'll need 2 SimpleDateFormats. One for the input format and one for the output format. Call .parse using the input format and .format using the output format.