By Sarah Vessels


2011-12-06 18:45:57 8 Comments

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.

8 comments

@Basil Bourque 2016-04-22 16:20:39

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" ) ;

Table of date-time types in Java, both modern and legacy


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.

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

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

Where to obtain the java.time classes?

Table of which java.time library to use with which version of Java or Android

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

@Basil Bourque 2017-11-06 04:35:47

@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.

@Rahul Raveendran 2019-10-15 09:14:22

If you guys are looking for a solution for Android, you can use the following code to get the epoch seconds from the timestamp string.

public static long timestampToEpochSeconds(String srcTimestamp) {
    long epoch = 0;

    try {
        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
            Instant instant = Instant.parse(srcTimestamp);
            epoch = instant.getEpochSecond();
        } else {
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'hh:mm:ss.SSSSSS'Z'", Locale.getDefault());
            sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
            Date date = sdf.parse(srcTimestamp);
            if (date != null) {
                epoch = date.getTime() / 1000;
            }
        }
    } catch (Exception e) {
        e.printStackTrace();
    }

    return epoch;
}

Sample input: 2019-10-15T05:51:31.537979Z

Sample output: 1571128673

@spencemw 2019-09-27 00:10:34

@John-Skeet gave me the clue to fix my own issue around this. As a younger programmer this small issue is easy to miss and hard to diagnose. So Im sharing it in the hopes it will help someone.

My issue was that I wanted to parse the following string contraining a time stamp from a JSON I have no influence over and put it in more useful variables. But I kept getting errors.

So given the following (pay attention to the string parameter inside ofPattern();

String str = "20190927T182730.000Z"

LocalDateTime fin;
fin = LocalDateTime.parse( str, DateTimeFormatter.ofPattern("yyyyMMdd'T'HHmmss.SSSZ") );

Error:

Exception in thread "main" java.time.format.DateTimeParseException: Text 
'20190927T182730.000Z' could not be parsed at index 19

The problem? The Z at the end of the Pattern needs to be wrapped in 'Z' just like the 'T' is. Change "yyyyMMdd'T'HHmmss.SSSZ" to "yyyyMMdd'T'HHmmss.SSS'Z'" and it works.

Removing the Z from the pattern alltogether also led to errors.

Frankly, I'd expect a Java class to have anticipated this.

@Ole V.V. 2019-09-27 10:55:32

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 2019-09-27 16:59:09

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 2019-09-27 17:02:17

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 2019-09-28 00:20:10

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.

@Jon Skeet 2011-12-06 18:49:10

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().

@Maroun 2015-06-03 07:57:24

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

@Jon Skeet 2015-06-03 08:23:07

@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 2016-01-22 07:41:19

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

@Jon Skeet 2016-01-22 07:41:55

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

@Jad Chahine 2016-09-21 18:41:04

@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 2016-09-21 18:41:54

@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 2016-09-21 18:43:43

@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 2016-09-21 18:48:06

@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 2016-11-12 11:28:02

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 2016-11-12 22:22:29

@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 2016-11-12 23:55:18

@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 2016-11-13 07:42:45

@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 2017-03-02 12:46:15

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

@Basil Bourque 2017-11-06 04:46:42

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 2017-11-06 06:25:36

@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 2018-12-18 17:15:16

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

@Jon Skeet 2018-12-18 18:04:14

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

@CodeBrew 2018-12-19 03:00:36

@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 2018-12-19 06:51:11

@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).

@Gapmeister66 2019-05-09 11:41:25

This technique translates java.util.Date to UTC format (or any other) and back again.

Define a class like so:

import java.util.Date;

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

public class UtcUtility {

public static DateTimeFormatter UTC = DateTimeFormat.forPattern("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'").withZoneUTC();


public static Date parse(DateTimeFormatter dateTimeFormatter, String date) {
    return dateTimeFormatter.parseDateTime(date).toDate();
}

public static String format(DateTimeFormatter dateTimeFormatter, Date date) {
    return format(dateTimeFormatter, date.getTime());
}

private static String format(DateTimeFormatter dateTimeFormatter, long timeInMillis) {
    DateTime dateTime = new DateTime(timeInMillis);
    String formattedString = dateTimeFormatter.print(dateTime);
    return formattedString;
}

}

Then use it like this:

Date date = format(UTC, "2020-04-19T00:30:07.000Z")

or

String date = parse(UTC, new Date())

You can also define other date formats if you require (not just UTC)

@Basil Bourque 2019-05-09 15:25:23

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.

@Gapmeister66 2019-10-04 14:20:38

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.

@Salih Kesepara 2019-01-08 10:19:40

You can use the following example.

    String date = "2011-08-12T20:17:46.384Z";

    String inputPattern = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'";

    String outputPattern = "yyyy-MM-dd HH:mm:ss";

    LocalDateTime inputDate = null;
    String outputDate = null;


    DateTimeFormatter inputFormatter = DateTimeFormatter.ofPattern(inputPattern, Locale.ENGLISH);
    DateTimeFormatter outputFormatter = DateTimeFormatter.ofPattern(outputPattern, Locale.ENGLISH);

    inputDate = LocalDateTime.parse(date, inputFormatter);
    outputDate = outputFormatter.format(inputDate);

    System.out.println("inputDate: " + inputDate);
    System.out.println("outputDate: " + outputDate);

@Basil Bourque 2019-09-24 05:37:28

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.

@VeryLazyBoy 2018-04-27 08:10:44

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");

@smparkes 2011-12-06 18:48:39

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

@user1997292 2016-01-28 09:55:48

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

@smparkes 2016-01-28 13:41:40

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.

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