How to parse DateTime in format yyyyMMddHHmmss to OffsetDateTime using DateFormatter

I have an API for JSON parsing which requires a DateTimeFormatter instance in order to parse date time strings to OffsetDateTime. However I always get an exception Unable to obtain ZoneOffset from TemporalAccessor: {},ISO resolved to 2021-08-17T13:26:49 of type java.time.format.Parsed The API uses OffsetDateTime.parse(String, DateFormatter).

// DateTimeFormatter instance to be provided to the API
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMddHHmmss");
// this is how the API uses the DateTimeFormatter instance
OffsetDateTime dateTime = OffsetDateTime.parse("20210817132649", formatter);

How do I have to create the DateTimeFormatter in order to deliver a ZoneOffset, so that the API is able to parse the DateTime correctly. The ZoneOffset may be UTC.

Well, the string you passed in does not contain zone information, while an OffsetDateTime requires zone information.

So you'll have to set a value for it.

You could use the DateTimeFormatterBuilder class, which then can be instructed to use some default value if a field is missing from the parsed information:

DateTimeFormatter formatter = new DateTimeFormatterBuilder()
    .parseDefaulting(ChronoField.OFFSET_SECONDS, 0)
    .appendPattern("yyyyMMddHHmmss")
    .toFormatter(Locale.ROOT);

You could also directly set an implied zone to the DateTimeFormatter:

DateTimeFormatter.ofPattern("yyyyMMddHHmmss").withZone(ZoneOffset.UTC);