Java LocalDateTime with offset

Question

The task is to convert current date time to that format:

  2023-06-28T12:00:01.545+0300

For this purporse I use the following approach:

 String currentDateTime =
    DateTimeFormatter.ISO_LOCAL_DATE_TIME
            .format(LocalDateTime.now().atOffset(ZoneOffset.UTC));

But it returns:

 2023-06-28T12:00:01.545

What am I missing?

Answer 1

ISO_LOCAL_DATE_TIME, as its name suggests, only produces local date times - date times without a zone/offset.

You should use ISO_DATE_TIME instead.

Also, getting the current LocalDateTime and then adding an offset to it doesn't make much sense to me, not to mention that you are adding an offset of 0 (UTC), instead of the +03:00 that you expect in your output.

To get a OffsetDateTime at +03:00 that represents the current instant, use the OffsetDateTime.now overload that takes a ZoneId.

String currentDateTime =
        DateTimeFormatter.ISO_DATE_TIME
                .format(OffsetDateTime.now(ZoneOffset.ofHours(3)));
        System.out.println(currentDateTime);

Example output:

2023-06-28T15:12:05.752631+03:00

If you want the offset to be in the format of +0300 instead, use a DateTimeFormatterBuilder, which allows you to specify a custom offset format.

String currentDateTime =
        new DateTimeFormatterBuilder()
                // first append the date time without an offset
                .append(DateTimeFormatter.ISO_LOCAL_DATE_TIME)
                // then append the offset - here I'm assuming you want "0000" for a 0 offset
                .appendOffset("+HHMM", "0000")
                .toFormatter()
                .format(OffsetDateTime.now(ZoneOffset.ofHours(3)));
        System.out.println(currentDateTime);