Converting a String to Java Date in ISO 8601 date-time format

I am trying to convert a string into an ISO 8601 date-time format. Currently, this code

String s1 = "2001-05-03T00:00:00+00:00";
Date firstAvailableDateTime = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssXXX").parse(s1);

gives me this result

2001-05-03T00:00:00.000+0000

However, this output is missing a colon in the timezone. The desired output is:

2001-05-03T00:00:00.000+00:00

According to https://docs.oracle.com/javase/8/docs/api/java/text/SimpleDateFormat.html, using "XXX" for the timezone should output a colon in the final date but it does not for me.

What am I missing?

I've looked at this solution but do not want to use Joda-Time since it may cause complications in the future moving between two date types.

Answer

OffsetDateTime.parse( "2001-05-03T00:00:00+00:00" )

Never use SimpleDateFormat, Date, Calendar, etc. These terrible classes were supplanted years ago by the java.time classes.

trying to convert a string into an ISO 8601 date-time format

String s1 = "2001-05-03T00:00:00+00:00"

Your Question is quite confused. Your input string is in standard ISO 8601 format. The T in the middle separates the year-month-day from the hour-minute-second, and the +00:00 at the end indicates an offset-from-UTC of zero hours and zero minutes, that is, UTC itself. All standard, all proper.

Perhaps you are conflating strings representing date-time values and date-time objects containing date-time values. A date-time object has no “format”; it has its own internally-defined representation of a date-time value. Only text has a format. A date-time class can parse a formatted string as input, and a date-time class can generate a formatted sting as output, but within the date-time there is no format at all.

OffsetDateTime

The java.time classes use the ISO 8601 formats by default when parsing/generating strings representing date-time values. So no need to specify a formatting pattern for such inputs.

OffsetDateTime odt = OffsetDateTime.parse( "2001-05-03T00:00:00+00:00" ) ;  

See this code run live at IdeOne.com.

odt.toString(): 2001-05-03T00:00Z

Z

There is a common abbreviation for an offset of zero: a simple Z letter, meaning UTC, and pronounced “Zulu”. Example: 2019-02-26T00:44:28Z

The Z is quite commonly used. But if for some reason you prefer the numeric +00:00, use DateTimeFormatter options.

COLON character

By the way, you mentioned the COLON character omitted from the offset: +0000. That is actually tolerated by the ISO 8601 standard. But I do not advise it. I have seen libraries and systems break on such inputs. Best to use full-length, hours and minutes, padding zeros, and the colon character: +00:00 rather than +0000, and -07:00 rather than -7.

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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 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.

Where to obtain the java.time classes?

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.