What is this date format? 2011-08-12T20:17:46.384Z

Question

I have the following date: 2011-08-12T20:17:46.384Z. What format is this? I'm trying to parse it with Java 1.4 via DateFormat.getDateInstance().parse(dateStr) and I'm getting

java.text.ParseException: Unparseable date: "2011-08-12T20:17:46.384Z"

I think I should be using SimpleDateFormat for parsing, but I have to know the format string first. All I have for that so far is yyyy-MM-dd, because I don't know what the T means in this string--something time zone-related? This date string is coming from the lcmis:downloadedOn tag shown on Files CMIS download history media type.

Solution 1

The T is just a literal to separate the date from the time, and the Z means "zero hour offset" also known as "Zulu time" (UTC). If your strings always have a "Z" you can use:

SimpleDateFormat format = new SimpleDateFormat(
    "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'", Locale.US);
format.setTimeZone(TimeZone.getTimeZone("UTC"));

Or using Joda Time, you can use ISODateTimeFormat.dateTime().

Solution 2

tl;dr

Standard ISO 8601 format is used by your input string.

Instant.parse ( "2011-08-12T20:17:46.384Z" ) 

ISO 8601

This format is defined by the sensible practical standard, ISO 8601.

The T separates the date portion from the time-of-day portion. The Z on the end means UTC (that is, an offset-from-UTC of zero hours-minutes-seconds). The Z is pronounced “Zulu”.

java.time

The old date-time classes bundled with the earliest versions of Java have proven to be poorly designed, confusing, and troublesome. Avoid them.

Instead, use the java.time framework built into Java 8 and later. The java.time classes supplant both the old date-time classes and the highly successful Joda-Time library.

The java.time classes use ISO 8601 by default when parsing/generating textual representations of date-time values.

The Instant class represents a moment on the timeline in UTC with a resolution of nanoseconds. That class can directly parse your input string without bothering to define a formatting pattern.

Instant instant = Instant.parse ( "2011-08-12T20:17:46.384Z" ) ;

---

---

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes. Hibernate 5 & JPA 2.2 support java.time.

Where to obtain the java.time classes?

• Java SE 8, Java SE 9, Java SE 10, Java SE 11, and later - Part of the standard Java API with a bundled implementation.
  • Java 9 brought some minor features and fixes.
• Java SE 6 and Java SE 7
  • Most of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
• Android
  • Later versions of Android (26+) bundle implementations of the java.time classes.
  • For earlier Android (<26), a process known as API desugaring brings a subset of the java.time functionality not originally built into Android.
    • If the desugaring does not offer what you need, the ThreeTenABP project adapts ThreeTen-Backport (mentioned above) to Android. See How to use ThreeTenABP….

Solution 3

Not sure about the Java parsing, but that's ISO8601: http://en.wikipedia.org/wiki/ISO_8601

Solution 4

There are other ways to parse it rather than the first answer. To parse it:

(1) If you want to grab information about date and time, you can parse it to a ZonedDatetime(since Java 8) or Date(old) object:

// ZonedDateTime's default format requires a zone ID(like [Australia/Sydney]) in the end.
// Here, we provide a format which can parse the string correctly.
DateTimeFormatter dtf = DateTimeFormatter.ISO_DATE_TIME;
ZonedDateTime zdt = ZonedDateTime.parse("2011-08-12T20:17:46.384Z", dtf);

or

// 'T' is a literal.
// 'X' is ISO Zone Offset[like +01, -08]; For UTC, it is interpreted as 'Z'(Zero) literal.
String pattern = "yyyy-MM-dd'T'HH:mm:ss.SSSX";

// since no built-in format, we provides pattern directly.
DateFormat df = new SimpleDateFormat(pattern);

Date myDate = df.parse("2011-08-12T20:17:46.384Z");

(2) If you don't care the date and time and just want to treat the information as a moment in nanoseconds, then you can use Instant:

// The ISO format without zone ID is Instant's default.
// There is no need to pass any format.
Instant ins = Instant.parse("2011-08-12T20:17:46.384Z");

Solution 5

java.time

You do not need DateTimeFormatter to parse the given date-time string.

Java SE 8 Date-Time API(java.time API or the modern Date-Time API) is based on ISO 8601 and does not require using a DateTimeFormatter object explicitly as long as the Date-Time string conforms to the ISO 8601 standards.

The Z in the string is the timezone designator for zero-timezone offset. It stands for Zulu and specifies the Etc/UTC timezone (which has the timezone offset of +00:00 hours).

The T in the string is just the Date-Time separator as per the ISO-8601 standards.

Demo:

import java.time.Instant;
import java.time.OffsetDateTime;
import java.time.ZonedDateTime;

public class Main {
    public static void main(String[] args) {
        String strDateTime = "2011-08-12T20:17:46.384Z";

        Instant instant = Instant.parse(strDateTime);
        OffsetDateTime odt = OffsetDateTime.parse(strDateTime);
        ZonedDateTime zdt = ZonedDateTime.parse(strDateTime);
        
        System.out.println(instant);
        System.out.println(odt);
        System.out.println(zdt);
    }
}

Output:

2011-08-12T20:17:46.384Z
2011-08-12T20:17:46.384Z
2011-08-12T20:17:46.384Z

Learn more about java.time, the modern Date-Time API^* from Trail: Date Time.

The legacy Date-time API

The legacy Date-time API (java.util Date-Time API and their formatting API, SimpleDateFormat) are outdated and error-prone. It is recommended to stop using them completely and switch to the modern Date-Time API^*.

For the sake of completeness, I've written a solution to parse this Date-Time string using the legacy API.

Do not use 'Z' in the pattern with the Date-Time parsing/formatting API.

As already described above, Z (without quotes) is the timezone designator for zero-timezone offset whereas 'Z' is just a character literal and it does not hold any meaning. Use the format, y-M-d'T'H:m:s.SSSXXX. Check the documentation to learn more about these symbols.

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

public class Main {
    public static void main(String[] args) throws ParseException {
        String strDateTime = "2011-08-12T20:17:46.384Z";

        SimpleDateFormat sdf = new SimpleDateFormat("y-M-d'T'H:m:s.SSSXXX", Locale.ENGLISH);
        Date date = sdf.parse(strDateTime);
        // ...
    }
}

Note that a java.util.Date object is not a real Date-Time object like the modern Date-Time types; rather, it represents the number of milliseconds since the standard base time known as "the epoch", namely January 1, 1970, 00:00:00 GMT (or UTC). Since it does not hold any format and timezone information, it applies the format, EEE MMM dd HH:mm:ss z yyyy and the JVM's timezone to return the value of Date#toString derived from this milliseconds value. If you need to print the Date-Time in a different format and timezone, you will need to use a SimpleDateFormat with the desired format and the applicable timezone e.g.

sdf.setTimeZone(TimeZone.getTimeZone("Etc/UTC"));
String formatted = sdf.format(date);
System.out.println(formatted); // 2011-8-12T20:17:46.384Z

Joda Date-Time API

Quoted below is a notice at the Home Page of Joda-Time:

Note that from Java SE 8 onwards, users are asked to migrate to java.time (JSR-310) - a core part of the JDK which replaces this project.

Again, for the sake of completeness, I've written a solution to parse this Date-Time string using the Joda Date-Time API.

import org.joda.time.DateTime;
import org.joda.time.format.DateTimeFormat;
import org.joda.time.format.DateTimeFormatter;

public class Main {
    public static void main(String[] args) {
        String dateTimeStr = "2011-08-12T20:17:46.384Z";
        DateTimeFormatter dtf = DateTimeFormat.forPattern("y-M-d'T'H:m:s.SSSZ").withOffsetParsed();
        DateTime dateTime = dtf.parseDateTime(dateTimeStr);
        System.out.println(dateTime);
    }
}

Output:

2011-08-12T20:17:46.384Z

---

^{* For any reason, if you have to stick to Java 6 or Java 7, you can use ThreeTen-Backport which backports most of the java.time functionality to Java 6 & 7. If you are working for an Android project and your Android API level is still not compliant with Java-8, check Java 8+ APIs available through desugaring and How to use ThreeTenABP in Android Project.}

View more solutions

Comments

[Maroun]

Why do we need the single quotes around T and Z?

[Jon Skeet]

@MarounMaroun: Basically we want those literal characters. It may not be necessary for T (I can't remember how SimpleDateFormat handles unknown specifiers) but for Z we want it to be the character 'Z' rather than "a UTC offset value" (e.g. "00").

[user989383]

java.lang.IllegalArgumentException: Illegal pattern character 'T' If you don't use single quotes around T or Z SimpleDateFormat throws this exception.

[Jon Skeet]

@user989383: Are you sure you quoted it as I did (with the apostrophes)? It should be absolutely fine.

[Admin]

Is this "2016-01-27T17:44:55UTC", ISO8601 too ?

[smparkes]

I don't believe so. It's close but UTC as a suffix isn't allowed. It has to be Z or a time zone offset, e.g., +0100. Z and UTC have the same meaning, though, so changing the UTC to Z would yield valid ISO 8601.

[Jad Chahine]

@JonSkeet: Hi John, I have this date and I wish to get a pattern of this date to convert it to another format :2017-03-10T06:00:00.000+11:00 PLEASE HELP

[Jon Skeet]

@JadChahine: So have you done a search for questions about converting date/time values from one format to another? There are hundreds (if not thousands) of similar questions on SO.

[Jad Chahine]

@JonSkeet: Yes really i search a lot but I don't found a format that takes into account the last characters of this date format which is +11:00

[Jon Skeet]

@JadChahine: Well that's the offset from UTC. So look in the documentation for SImpleDateFormat... and then you need to work out which time zone you're actually interested in.

[nyedidikeke]

Point of correction please (for clarity): the Z is the zone designator for the zero UTC offset and does not means "Zulu time". Reference is made to Zulu time as Zulu is the NATO phonetic alphabet word for letter Z (26th letter of the English alphabet).

[Jon Skeet]

@nyedidikeke: In the Wikipedia page you linked to, it shows "Zulu time zone" for UTC. I'm not sure what you believe you're correcting.

[nyedidikeke]

@JonSkeet: it may generate an unnecessary debate; not disputing your answer but intended to draw attention the Z which got its letter initial from "zero UTC offset". Letter Z is referred to as "Zulu" in the NATO phonetic alphabet. In turns, the military approach to refer to the zero UTC offset is anchored on letter Z which they identify as Zulu, earning it their coded name: Zulu time zone. It is important to note that the Z has not lost its meaning and still is the zone designator for the zero UTC offset as Zulu time zone (from Z) is simply an inherited coded language to refer to it.

[Jon Skeet]

@nyedidikeke: I still disagree about whether anyone else is ever going to care about the distinction with reference to my answer, but I've updated it. I'm not going to go into all the detail though, as the history is broadly irrelevant to the answer.

[Daniel Hári]

You can test this date pattern online: dateformatter.danielhari.com/…

[Basil Bourque]

@star The “Zulu” comes from military and aviation tradition where 25 letters of the alphabet A-Z (no "J"), each letter having a pronounceable name, represents their version of time zones. The "Zulu" zone is zero hours offset from UTC. See this and this.

[Basil Bourque]

Good Answer, but now outdated. The java.time classes supplant both the legacy date-classes bundled with the earliest versions of Java as well as the Joda-Time project.

[Jon Skeet]

@Basil: Yes, but I'm not going to go and edit every answer from years ago to use java.time. As the question specifically talks about Java 1.4, I think it stands reasonably to answer that specific question.

[CodeBrew]

Note that setTimeZene is very important as Z means the zero offset from this timezone.

[Jon Skeet]

@CodeBrew: Not "from this time zone" but from UTC.

[CodeBrew]

@JonSkeet at first I didn't setTimeZone to UTC, then my date formatter converted a date string in the format like 2011-08-12T15:17:46.384Z to 2011-08-12T20:17:46.384Z, effectively thinking the original string I gave was in my own timezone (EST). Once I setTimeZone to UTC the converted result became correct. Of course I was using Swift, but the syntax is close to what you posted here. Could you try it in Java without setTimeZone and compare the difference? Thanks

[Jon Skeet]

@CodeBrew: I wasn't saying that the call to setTimeZone wasn't required. It absolutely is. I'm saying that Z doesn't mean "the zero offset from this time zone" - it means "UTC" (or "zero offset from UTC" if you want).

[Basil Bourque]

Both java.util.Date and the Joda-Time project were supplanted years ago by the modern java.time classes defined in JSR 310. The advice here is long outdated.

[Basil Bourque]

You should not be putting apostrophes around the Z. That means to expect but ignore that letter. But that letter should not be ignored. That letter provides valuable information, the fact that the string was intended for UTC, an offset of zero. Your format is discarding this important fact. Furthermore, there is no need to even bother defining this formatting pattern. A formatter for this pattern is built in.

[Ole V.V.]

This has already been asked and answered here and here. And your solution is wrong. While T is a literal and needs to be quoted, Z is an offset (of zero) and needs to be parsed as such, or you will get wrong results. I don’t know what you mean that it hasn’t been anticipated, I believe that it has.

[Basil Bourque]

No, no, no, do not ignore the Z. You are discarding valuable information. Processing a date-time value while ignoring time zone or offset-from-UTC is like processing an amount of money while ignoring currency!

[Basil Bourque]

The T merely separates the date portion from the time-of-day portion, and adds no meaning. The Z on the other hand definitely adds meaning.

[spencemw]

Ole, thanks for the links. Ill certainly read those. And I accept that I certainly could be wrong as a youngin. All Im saying is that wrapping the Z in single quotes like a char in the pattern solved the error. My criticism is that whoever designed "pattern" part of the class could have coded around the presence or absence of 'Z' (or a diff time zone?) and 'T' being wraped in ' ' or not. Because they didnt its unique. The format Im dealing with comes from JSON from a commercial API parsed to a string. But I need to parse all that into date time calendar etc to make them more useful.

[Gapmeister66]

java.time was introduced in Java 8. This question specifically references Java 1.4 and therefore I have deliberately avoided use of the newer classes. This solution caters for older code bases. I suppose the author could move his codebase to Java 8 but that is not always straightforward, efficient or necessary.

[Ahmed Mahmoud]

Thanks for your time and effort. That helped me a lot

[Faisal]

the LocalDateTime.parse("2021-11-22T09:00:00.000Z") throws exception while parsing. Any suggestion, how to format the same input using java.time to format to "EEEE, MMMM dd"? thanks.

[Basil Bourque]

@Faisal Your attempt to parse a moment (a date with time and offset) as a LocalDateTime is illogical. A LocalDateTime is not a moment, not a specific point on the timeline, because it has no concept of an offset-from-UTC nor time zone. Your input should be parsed as an Instant, like this: Instant.parse("2021-11-22T09:00:00.000Z").

[Faisal]

Make sense. Can an Instance be parsed to expected format?

[Basil Bourque]

@Faisal Apply a time zone (ZoneId) through which you want to perceive a date. This gets you a ZonedDateTime. Extract from that a LocalDate. Use a DateTimeFormatter to generate text in any format you desire, or automatically localize. All that has been covered many times already on Stack Overflow.

[Bilawal muzaffar]

Amazing work like charm, Thankyou