How do I tell Joda Time that the time I am giving it is for a specific time zone offset, even though the offset isn't given in the String?

Question

I am working with an API that provides me with a ModifyDate field that is being given in CST (-06:00), but when passing the string in to Joda time and setting the time zone to America/Phoenix, Joda time thinks that the date/time I gave it is in UTC time zone because there is no offset information being given by the API (the time being returned is in CST, confirmed with the developers).

Side note: I am in Arizona where we do not recognize daylight savings time, so I can't just apply a static offset of -1 hour.

Here's an example of what I'm dealing with:

Field returned by the API:

"modifyDate": "2020-02-11T12:23:39.817Z"

Trying to format the date with Joda time:

DateTime time1 = new DateTime("2020-02-11T12:23:39.817Z", DateTimeZone.forID("CST6CDT"));
System.out.println(time1);

DateTime time2 = new DateTime(time1, DateTimeZone.forID("America/Phoenix"));
System.out.println(time2);

System.out.println("----------------------------");

DateTime time3 = DateTime.parse("2020-02-11T12:23:39.817Z");
System.out.println(time3);
System.out.println(time3.toInstant());
System.out.println(time3.withZone(DateTimeZone.forID("America/Phoenix")));
System.out.println(time3.toDateTimeISO());
System.out.println(time3.toDate());

System.out.println("--------------------------------");

Output:

2020-02-11T06:23:39.817-06:00
2020-02-11T05:23:39.817-07:00
----------------------------
2020-02-11T12:23:39.817Z
2020-02-11T12:23:39.817Z
2020-02-11T05:23:39.817-07:00
2020-02-11T12:23:39.817Z
Tue Feb 11 05:23:39 MST 2020
--------------------------------

As you can see in the first two outputs, by trying to apply the time zone for CST, the time provided is offset by -6 (to be expected if the time provided was in UTC). By setting the time zone to America/Phoenix, the offset is -7 (also to be expected). However, as I mentioned, the time that I am passing into DateTime is not UTC, it is CST.

How can I tell DateTime (or even some other library, for that matter) that the time being provided is in CST? Again, keeping in mind that when daylight savings time changes, the offset needs to be managed properly.

Answer 1

In this case, the time being provided by the API was incorrectly being provided as UTC, even though the time is CST, as pointed out by OleV.V. The cleanest solution to this problem was to use DateTime.withZoneRetainFields(), as mentioned by shmosel.

For whatever reason, however, if I created the DateTime object by using the constructor, I couldn't adjust the time zone with withZoneRetainFields(), instead, I had to use DateTime.parse().

I adjusted for the time zone being off by using the following logic:

DateTime time4 = DateTime.parse("2020-02-11T12:23:39.817Z").withZoneRetainFields(DateTimeZone.forID("CST6CDT"));
System.out.println(time4);
System.out.println(time4.withZone(DateTimeZone.forID("America/Phoenix")));

Output (correct)

2020-02-11T12:23:39.817-06:00
2020-02-11T11:23:39.817-07:00

Hopefully, this will help someone else if they come across the same problem.