如何获得两个date_time之间的差异

Question

I want to get the difference in seconds between end_date_time and system_date_time using JAVA, for example:

if 
    end_date_time = 2015-02-21 13:00:00
    system_date_time = 2015-02-20 13:00:00
then 
    difference = 86400

Please tell how can I do this?

Answer 1

If you have a Date type already, it's as simple as:

(System.currentTimeMillis() - myDate.getTime()) / 1000;

If you have a string and need to convert it to a date, you use a SimpleDateFormat instance:

String dateString = "2015-02-21 13:00:00" // end_date_time
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-mm-dd hh:mm:ss");
Date myDate = sdf.parse(dateString);

If you're using Java8, this is much easier:

String dateString = "2007-12-03T10:15:30.00Z";
Instant.now().until(Instant.parse(dateString), ChronoUnit.SECONDS);

Your dateString must be parseable in the ISO format, though:

"yyyy-mm-ddThh:mm:ss.SZ"