Kotlin date parsing is not working properly-CodePudding

So I have been looking up on how to properly parse an incoming datetime, problem is that this string contains the zone as well which apparently can't be parsed for some reason. To give an example of the incoming date time string: 2021-10-05T10:00:00.0000000

Now I tried to the following:

var dateTimeString = "2021-10-05T10:00:00.0000000"
var formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSZ")
var date = LocalDate.parse(dateTimeString, formatter)

I tried replacing Z with nothing and with ZZZZ, but that didn't work I assume it doesn't work because of the plus or minus sign not being present. FYI, I receive the date in this format because of the Microsoft Graph API when retrieving the calendar events.

Any idea as to how this date should be formatted properly?

CodePudding user response：

As I can see from docs you've provided https://docs.microsoft.com/en-us/graph/api/resources/datetimetimezone?view=graph-rest-1.0

dateTime    String  A single point of time in a combined date and time representation ({date}T{time}; for example, 2017-08-29T04:00:00.0000000).
timeZone    String  Represents a time zone, for example, "Pacific Standard Time". See below for more possible values.

dateTime object has no zone encoded. And all 7 zeroes represent fractions of a second. In such case it's regular ISO_DATE_TIME and you don't need to create your own formatter.

The following code should work

var dateTimeString = "2021-10-05T10:00:00.0000000"
var date = LocalDate.parse(dateTimeString, DateTimeFormatter.ISO_DATE_TIME)

CodePudding user response：

For the case that the last 4 digits in your example String are not representing a time zone:

Parse it without a formatter (no need since it would be perfect ISO standard if the last 4 digits are just additional fractions of second), but also consider the time zone you get with the JSON:

import java.time.LocalDateTime
import java.time.ZoneId
import java.time.ZonedDateTime
import java.time.format.DateTimeFormatter

fun main() {
    // the time String from JSON
    var dateTimeString = "2021-10-05T10:00:00.0000000"
    // the zone from JSON (may not always work, but does with UTC)
    var timeZone = "UTC"
    // create the zone from the timezone String
    var zoneId = ZoneId.of(timeZone)
    // then parse the time String using plain LocalDateTime and add the zone afterwards
    var zdt: ZonedDateTime = LocalDateTime.parse(dateTimeString).atZone(zoneId)
    // print some results
    println("Full ZonedDateTime: ${zdt.format(DateTimeFormatter.ISO_ZONED_DATE_TIME)}")
    println("(Local)Date only:   ${zdt.toLocalDate()}")
}

Full ZonedDateTime: 2021-10-05T10:00:00Z[UTC]
(Local)Date only:   2021-10-05

Please note that parsing the time zones currently supported by Windows won't work this easy (except from UTC), but the time zones supported by the calendar API are (mostly) sufficient for the creation of a java.time.ZoneId.