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How to Convert "2021-05-14T13:42:48.000Z" string to Date Object?

I am trying to convert "2021-05-14T13:42:48.000Z" string to Date Object.
I have tried this:
DateFormat dateFormat = new SimpleDateFormat("YYYY-MM-DDHH:MM:SS");
And also this, which i saw on stackoverflow only:-
DateFormat dateFormat = new SimpleDateFormat("YYYY-MM-DD'T'HH:MM:SS'A'");
But none of it worked.
How can i convert this string to my date object?

Assuming your date string always represents a UTC time (with the 'Z'), you can use format string:
yyyy-MM-dd'T'HH:mm:ss.SSSZ
but you'll first need to replace the Z in your date string with the fixed timezone "+0000", as in "2021-05-14T13:42:48.000+0000".
Try this:
String myDateString = "2021-05-14T13:42:48.000Z"
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ", Locale.US);
Date myDate = dateFormat.parse (myDateString.replace("Z","+0000"));
This will return a date correctly adjusted for your current timezone, in my case 9:42:48am EDT.
There is a more detailed discussion at Converting ISO 8601-compliant String to java.util.Date which you may find useful.

You have used the date-time format incorrectly. It's important to note that the date-time formats have different meanings between capitalized and small letters.
For example: Capital MM means months, whereas small mm means minutes.
To know more about the date formats, you can refer this:
https://cheatography.com/pezmat/cheat-sheets/date-time-formats/pdf/
or this:
https://devhints.io/datetime
And the answer for your case is:
DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");

Please do not use SimpleDateFormat or even java.date. All these classes are deprecated.
Instead, rely on the Android available java.time package.
In short:
val source = "2021-05-14T13:42:48.000Z"
val parsed = ZonedDateTime.parse(source)
This will correctly parse the timezone (Z for Zulu/UTC/GMT).
You can verify this, by simply converting the parsed Zoned date time into, for example, Europe/Amsterdam time (which is +2).
val source = "2021-05-14T13:42:48.000Z"
val parsed = ZonedDateTime.parse(source)
parsed.toString() // prints: 2021-05-14T13:42:48Z
parsed.zone // prints: "Z"
ZoneId.of(parsed.zone.id) // returns the ZoneOffset "Z" (correct)
// Convert to Amsterdam Time
val amsterdamDateTime = parsed.withZoneSameInstant(ZoneId.of("Europe/Amsterdam"))
amsterdamDateTime.toString() // prints: 2021-05-14T15:42:48+02:00[Europe/Amsterdam] (2 hours ahead of the Zulu time, also correct).
parsed.format(DateTimeFormatter.ISO_DATE_TIME).toString() // Prints: 2021-05-14T13:42:48Z (correct)
So as you can see, these classes do the right thing (most of the time).
I suggest you use them.

Kotlin convert DateTime to 10 digit TimeStamp

I'm trying to find out how I can convert DateTime to 10 digit timestamp in Kotlin (Android Studio), I can't find any equivalent of it in Kotlin.
For example:
I have a val with date-time value like :
val dateTime = "2020-12-13 17:54:00"
Now I want to convert it to 10 digit timestamp like "1607842496"
Please give me a simple sample to show how I can resolve this problem. Thanks in advance.

Use the SimpleDateFormat class to parse your date String to a Date object. You can then get the timestamp (in milliseconds) from that Date object like so:
val dateTime = "2020-12-13 17:54:00"
val simpleDateFormat = SimpleDateFormat("yyyy-MM-dd HH:mm:ss", Locale.getDefault())
val date = simpleDateFormat.parse(dateTime)
val timestamp = date?.time
Divide the timestamp by a 1000 to get the 10 digit (in seconds) timestamp.

How to convert time from server to local zone with kotlin?

I get a time from server and I want to change it to Local zone How can I do that with Kotlin ?
Time coming from the server is like "2020-09-01T13:16:33.114Z"
Here's my code:
val dateStr = order.creationDate
val df = SimpleDateFormat("dd-MM-yyyy HH:mm aa", Locale.getDefault())
df.timeZone = TimeZone.getDefault()
val date = df.parse(dateStr)
val formattedDate = df.format(date)
textViewDateOrderDetail.text = formattedDate
order.creationDate : Time from server

tl;dr
This will convert the example String to the system default time zone:
import java.time.ZonedDateTime
import java.time.ZoneId
fun main() {
// example String
val orderCreationDate = "2020-09-01T13:16:33.114Z"
// parse it to a ZonedDateTime and adjust the zone to the system default
val localZonedDateTime = ZonedDateTime.parse(orderCreationDate)
.withZoneSameInstant(ZoneId.systemDefault())
// print the adjusted values
println(localZonedDateTime)
}
The output depends on the system default time zone, in the Kotlin Playground, it produces the following line:
2020-09-01T13:16:33.114Z[UTC]
which obviously means the Kotlin Playground is playing in UTC.
A little more...
It's strongly recommended to use java.time nowadays and to stop using the outdated libraries for datetime operations (java.util.Date, java.util.Calendar along with java.text.SimpleDateFormat).
If you do that, you can parse this example String without specifying an input format because it is formatted in an ISO standard.
You can create an offset-aware (java.time.OffsetDateTime) object or a zone-aware one
(java.time.ZonedDateTime), that's up to you. The following example(s) show(s) how to parse your String, how to adjust a zone or an offset and how to print in a different format:
import java.time.OffsetDateTime
import java.time.ZonedDateTime
import java.time.ZoneId
import java.time.ZoneOffset
import java.time.format.DateTimeFormatter
fun main() {
// example String
val orderCreationDate = "2020-09-01T13:16:33.114Z"
// parse it to an OffsetDateTime (Z == UTC == +00:00 offset)
val offsetDateTime = OffsetDateTime.parse(orderCreationDate)
// or parse it to a ZonedDateTime
val zonedDateTime = ZonedDateTime.parse(orderCreationDate)
// print the default output format
println(offsetDateTime)
println(zonedDateTime)
// adjust both to a different offset or zone
val localZonedDateTime = zonedDateTime.withZoneSameInstant(ZoneId.of("Brazil/DeNoronha"))
val localOffsetDateTime = offsetDateTime.withOffsetSameInstant(ZoneOffset.ofHours(-2))
// print the adjusted values
println(localOffsetDateTime)
println(localZonedDateTime)
// and print your desired output format (which doesn't show a zone or offset)
println(localOffsetDateTime.format(
DateTimeFormatter.ofPattern("dd-MM-uuuu hh:mm a")
)
)
println(localZonedDateTime.format(
DateTimeFormatter.ofPattern("dd-MM-uuuu hh:mm a")
)
)
}
The output is
2020-09-01T13:16:33.114Z
2020-09-01T13:16:33.114Z
2020-09-01T11:16:33.114-02:00
2020-09-01T11:16:33.114-02:00[Brazil/DeNoronha]
01-09-2020 11:16 AM
01-09-2020 11:16 AM
For a conversion to the system zone or offset, use ZoneId.systemDefault() or ZoneOffset.systemDefault() instead of hard coded ones. Pay attention to the ZoneOffset since it does not necessarily give the correct one because only a ZoneId considers daylight saving time.
For more information, see this question and its answer
For further and more accurate information about formats to be defined for parsing or formatting output, you should read the JavaDocs of DateTimeFormatter.

Which Locale (SimpleDateFormat) is "yyyy-MM-dd"?

I want to convert a date into "yyyy-MM-dd". I am using
val parser = SimpleDateFormat("dd-MMM-yyyy") // The original format
val formatter = SimpleDateFormat("yyyy-MM-dd")
val output = formatter.format(parser.parse(etDOB.text.toString()))
as given here. But Android studio is warning me to use SimpleDateFormat(String, Locale). Which locale should I use to get output into "yyyy-MM-dd"?
Or is there a better way to achieve this (API 21)? I also have the date in a calendar instance.

Use Locale.getDefault() in SimpleDateFormat
val formatter = SimpleDateFormat("yyyy-MM-dd", Locale.getDefault())

ThreeTenABP not parsing date

I am trying to convert ISO 8601 time into something human readable and in the local timezone of the Android device.
String date = "2016-09-24T06:24:01Z";
LocalDate test = LocalDate.parse(date, ISO_INSTANT);
But it returns:
method threw 'org.threeten.bp.format.DateTimeParseException' exception
From reading http://www.threeten.org/threetenbp/apidocs/org/threeten/bp/format/DateTimeFormatter.html#ISO_INSTANT it seems like what I'm doing should be possible.
What am I doing wrong?
Edit
Expanded exception error:
Unable to obtain LocalDate from TemporalAccessor: DateTimeBuilder[fields={MilliOfSecond=0, NanoOfSecond=0, InstantSeconds=1474698241, MicroOfSecond=0}, ISO, null, null, null], type org.threeten.bp.format.DateTimeBuilder
Edit 2
The solution is in the answer below. For anyone that stumbles across this, if you want to specify a custom output format you can use:
String format = "MMMM dd, yyyy \'at\' HH:mm a";
String dateString = DateTimeFormatter.ofPattern(format).withZone(ZoneId.systemDefault()).format(instant);

#alex answer is correct. Here is a working example.
Instant represents a point in time. To convert to any other local types you will need timezone.
String date = "2016-09-24T06:24:01Z";
This date string is parsed using the DateTimeFormatter#ISO_INSTANT internally.
Instant instant = Instant.parse(date);
From here you can convert to other local types just using timezone ( defaulting to system time zone )
LocalDateTime localDateTime = instant.atZone(ZoneId.systemDefault()).toLocalDateTime();
LocalDate localDate = instant.atZone(ZoneId.systemDefault()).toLocalDate();
LocalTime localTime = instant.atZone(ZoneId.systemDefault()).toLocalTime();
Alternatively, you can use static method to get to local date time and then to local date and time.
LocalDateTime localDateTime = LocalDateTime.ofInstant(instant, ZoneId.systemDefault());
LocalDate localDate = localDateTime.toLocalDate();
LocalTime localTime = localDateTime.toLocalTime();

You need to use Instant.parse().
This will give you an Instant that you can combine with a time zone to create a LocalDate.

In Kotlin:
Converts to LocalDateTime directly based on your local time zone::
val instant: Instant = Instant.parse("2020-04-21T02:22:04Z")
val localDateTime = instant.atZone(ZoneId.systemDefault()).toLocalDateTime()
Converts to Date and time separately based on your local time zone:
val localDate: LocalDate = instant.atZone(ZoneId.systemDefault()).toLocalDate()
val localTime: LocalTime = instant.atZone(ZoneId.systemDefault()).toLocalTime()