CODEWITHSUNDEEP
javaandroiddatetimesimpledateformat
Rubick
Rubick

Reputation: 306

Android - Converting current date and time with timezone

How can I convert the current time like this kind of format 2018-09-21T01:56:57.926986+00:00 on android?. I'm using DateFormat but I don't know how to add an timezone on it. This is the code that I'm using when getting the current date and time

DateFormat dateFormat = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss");
                                    Date date = new Date();
                                    String curDate = dateFormat.format(date);

Thanks in advance

Upvotes: 0

Views: 2941

Answers (1)

Basil Bourque
Basil Bourque

Reputation: 338775

tl;dr

Use java.time classes.

OffsetDateTime            // Represent a moment as a date, a time-of-day, and an offset-from-UTC (a number of hours, minutes, seconds) with a resolution as fine as nanoseconds.
.now(                     // Capture the current moment. 
    ZoneOffset.UTC.       // Specify your desired offset-from-UTC. Here we use an offset of zero, UTC itself, predefined as a constant.
)                         // Returns a `OffsetDateTime` object.
.format(                  // Generate text in a `String` object representing the date-time value of this `OffsetDateTime` object.
    DateTimeFormatter.ofPattern( "uuuu-MM-dd'T'HH:mm:ss.SSSSSSxxxxx" , Locale.US )
)                         // Returns a `String` object.

2018-09-27T05:39:41.023987+00:00

Or, use Z for UTC.

Instant.now().toString()

2018-09-27T05:39:41.023987Z

java.time

The modern approach uses the java.time that supplanted the terrible old date-time classes.

Specifically:

  • Use Instant or OffsetDateTime instead of java.util.Date.
  • Use DateTimeFormatter instead of `SimpleDateFormat.

Get the current time in UTC. We use the OffsetDateTime class rather than Instant for more flexible formatting when generating text.

ZoneOffset offset = ZoneOffset.UTC;
OffsetDateTime odt = OffsetDateTime.now( offset );

Define a formatting pattern to match your desired output. Note that the built-in formatting patterns use Z as standard shorthand for +00:00. The Z means UTC and is pronounced “Zulu”. This Zulu time format is quite common. I suggest using such formats with Z. But you asked explicitly for the long version of an offset-from-UTC of zero, so we must use a custom DateTimeFormatter object.

DateTimeFormatter f = DateTimeFormatter.ofPattern( "uuuu-MM-dd'T'HH:mm:ss.SSSSSSxxxxx" , Locale.US );
String output = odt.format( f );

2018-09-27T05:39:41.023987+00:00

FYI, the formats discussed here comply with the ISO 8601 standard.

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?

Upvotes: 4

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