Retrieve two equal dates from SimpleDateFormat in java

Question

I made this snippet to show my problem:

import java.text.SimpleDateFormat;

public class Foo {
    public static void main(String[] args) {

        SimpleDateFormat formatter = new SimpleDateFormat("mm hh dd MM yyyy");
        String date1 = "1412293500";
        String date2 = "1412336700";
        String dateString1 = formatter.format(Long.parseLong(date1 + "000"));
        String dateString2 = formatter.format(Long.parseLong(date2 + "000"));
        System.out.println(dateString1 + " " + dateString2);

    }
}

date1 and date2 are expressed in seconds, so I'm expecting two different dates in output, but the dates are printed the same. I checked inside this online tool, and as you can see the dates are related to two different days.

How can I solve this?

Answer 1

The difference between your two timestamps is exactly 12 hours.

The h identifier in SimpleDateFormat formats the hours in AM/PM (1-12), so you actually do not output the real difference: the date was shifted from AM to PM.

Try with the k or H identifier which formats the hour in day as (1-24) or (0-23).

SimpleDateFormat formatter = new SimpleDateFormat("mm kk dd MM yyyy");
String date1 = "1412293500";
String date2 = "1412336700";
String dateString1 = formatter.format(Long.parseLong(date1 + "000"));
String dateString2 = formatter.format(Long.parseLong(date2 + "000"));
System.out.println(dateString1 + " " + dateString2); // prints 45 01 03 10 2014 45 13 03 10 2014

You could also output the AM/PM marker with the a identifier like this:

SimpleDateFormat formatter = new SimpleDateFormat("mm hh dd MM yyyy aa");
String date1 = "1412293500";
String date2 = "1412336700";
String dateString1 = formatter.format(Long.parseLong(date1 + "000"));
String dateString2 = formatter.format(Long.parseLong(date2 + "000"));
System.out.println(dateString1 + " " + dateString2); // prints 45 01 03 10 2014 AM 45 01 03 10 2014 PM