Converting ISO 8601-compliant String to java.util.

Question

I am trying to convert an ISO 8601 formatted String to a java.util.Date.

I found the pattern yyyy-MM-dd'T'HH:mm:ssZ to be ISO8601-compliant if used with a Locale (compare sample).

However, using the java.text.SimpleDateFormat, I cannot convert the correctly formatted String 2010-01-01T12:00:00+01:00. I have to convert it first to 2010-01-01T12:00:00+0100, without the colon.

So, the current solution is

SimpleDateFormat ISO8601DATEFORMAT = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ", Locale.GERMANY);
String date = "2010-01-01T12:00:00+01:00".replaceAll("\\+0([0-9]){1}\\:00", "+0$100");
System.out.println(ISO8601DATEFORMAT.parse(date));

which obviously isn't that nice. Am I missing something or is there a better solution?

---

Answer

Thanks to JuanZe's comment, I found the Joda-Time magic, it is also described here.

So, the solution is

DateTimeFormatter parser2 = ISODateTimeFormat.dateTimeNoMillis();
String jtdate = "2010-01-01T12:00:00+01:00";
System.out.println(parser2.parseDateTime(jtdate));

Or more simply, use the default parser via the constructor:

DateTime dt = new DateTime( "2010-01-01T12:00:00+01:00" ) ;

To me, this is nice.

Answer 1

The DatatypeConverter solution doesn't work in all VMs. The following works for me:

javax.xml.datatype.DatatypeFactory.newInstance().newXMLGregorianCalendar("2011-01-01Z").toGregorianCalendar().getTime()

I've found that joda does not work out of the box (specifically for the example I gave above with the timezone on a date, which should be valid)

Answer 2

Do it like this:

public static void main(String[] args) throws ParseException {

    String dateStr = "2016-10-19T14:15:36+08:00";
    Date date = javax.xml.bind.DatatypeConverter.parseDateTime(dateStr).getTime();

    System.out.println(date);

}

Here is the output:

Wed Oct 19 15:15:36 CST 2016

Answer 3

The Jackson-databind library also has ISO8601DateFormat class that does that (actual implementation in ISO8601Utils.

ISO8601DateFormat df = new ISO8601DateFormat();
Date d = df.parse("2010-07-28T22:25:51Z");

Answer 4

Also you can use the following class -

org.springframework.extensions.surf.util.ISO8601DateFormat


Date date = ISO8601DateFormat.parse("date in iso8601");

Link to the Java Doc - Hierarchy For Package org.springframework.extensions.surf.maven.plugin.util

Answer 5

The workaround for Java 7+ is using SimpleDateFormat:
DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSX", Locale.US);

This code can parse ISO8601 format like:

• 2017-05-17T06:01:43.785Z
• 2017-05-13T02:58:21.391+01:00

But on Java6, SimpleDateFormat doesn't understand X character and will throw
IllegalArgumentException: Unknown pattern character 'X'
We need to normalize ISO8601 date to the format readable in Java 6 with SimpleDateFormat.

public static Date iso8601Format(String formattedDate) throws ParseException {
    try {
        DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSX", Locale.US);
        return df.parse(formattedDate);
    } catch (IllegalArgumentException ex) {
        // error happen in Java 6: Unknown pattern character 'X'
        if (formattedDate.endsWith("Z")) formattedDate = formattedDate.replace("Z", "+0000");
        else formattedDate = formattedDate.replaceAll("([+-]\\d\\d):(\\d\\d)\\s*$", "$1$2");
        DateFormat df1 = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ", Locale.US);
        return df1.parse(formattedDate);
    }
}

Method above to replace [Z with +0000] or [+01:00 with +0100] when error occurs in Java 6 (you can detect Java version and replace try/catch with if statement).

Answer 6

tl;dr

OffsetDateTime.parse ( "2010-01-01T12:00:00+01:00" )

Using java.time

The new java.time package in Java 8 and later was inspired by Joda-Time.

The OffsetDateTime class represents a moment on the timeline with an offset-from-UTC but not a time zone.

OffsetDateTime odt = OffsetDateTime.parse ( "2010-01-01T12:00:00+01:00" );

Calling toString generates a string in standard ISO 8601 format:

2010-01-01T12:00+01:00

To see the same value through the lens of UTC, extract an Instant or adjust the offset from +01:00 to 00:00.

Instant instant = odt.toInstant();  

…or…

OffsetDateTime odtUtc = odt.withOffsetSameInstant( ZoneOffset.UTC );

Adjust into a time zone if desired. A time zone is a history of offset-from-UTC values for a region, with a set of rules for handling anomalies such as Daylight Saving Time (DST). So apply a time zone rather than a mere offset whenever possible.

ZonedDateTime zonedDateTimeMontréal = odt.atZoneSameInstant( ZoneId.of( "America/Montreal" ) );

---

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.

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.

Where to obtain the java.time classes?

• Java SE 8, Java SE 9, Java SE 10, and later
  • Built-in.
  • Part of the standard Java API with a bundled implementation.
  • Java 9 adds some minor features and fixes.
• Java SE 6 and Java SE 7
  • Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
• Android
  • Later versions of Android bundle implementations of the java.time classes.
  • For earlier Android (<26), the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). See How to use ThreeTenABP….

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.

---