21

Is there a Java equivalent of DateTime.MinValue and DateTime.Today in the Java Date class? Or a way of achieving something similar?

I've realised how spoilt you are with the .NET datetime class, I also need the equivalent of AddDays(), AddMonths().

Improve this question
1

6 Answers 6

Reset to default
23

The de-facto Java datetime API is joda-time.

With it, you can get the current date/time by just constructing new DateTime().

Similarly, Without it, you can use Calendar.getInstance() or new Date() to obtain the current date/time.

MinValue can be Calendar.getInstance(0) / new Date(0). This would use the default chronology - i.e. since January 1st, 1970. Since MinValue returns Januar 1st, year 1, you can do that be simply specifying this date, using the appropriate constructor of DateTime.

Improve this answer
Sign up to request clarification or add additional context in comments.

7 Comments

+1. Java built in dates are bad. Take the 3 extra seconds to build around Joda time, and you will be much happier.
I've heard of Jon Skeet's api, but is this android friendly?
I believe it is completely android-friendly. (Jon Skeet has made a port of JodaTime to .NET (noda-time))
I thought Joda time was his not Noda time, I'll give it a try
I could just use the epoch as the min value (I'm looking for something to indicate no date has been set), I'm not so sure about the opposite though
|
4

The other Answers may be correct but use outmoded classes.

java.time

The old date-time classes (java.util.Date/.Calendar etc.) were supplanted by Joda-Time, which in turn has been supplanted by the java.time framework built into Java 8 and later. The java.time classes are inspired by Joda-Time, defined by JSR 310, extended by the ThreeTen-Extra project, back-ported to Java 6 & 7 by the ThreeTen-Backport project, and adapted to Android in the ThreeTenABP project. See Tutorial.

To get the current moment on the timeline in UTC with a resolution of nanoseconds, use Instant.

Instant now = Instant.now();

Instant has three constants:

  • EPOCH – 1970-01-01T00:00:00Z
  • MIN – -1000000000-01-01T00:00Z
  • MAX – 1000000000-12-31T23:59:59.999999999Z

To get the current moment for an offset-from-UTC, apply a ZoneOffset to get an OffsetDateTime.

OffsetDateTime now = OffsetDateTime.now( ZoneOffset.of( "-04:00" ) );

Better to apply a full time zone (offset plus rules for anomalies such as Daylight Saving Time) if known. Apply a ZoneId to get a ZonedDateTime.

ZonedDateTime now = ZonedDateTime.now( ZoneId.of( "America/Montreal" ) );

You can perform arithmetic.

ZonedDateTime dayLater = now.plusDays( 1 ); ZonedDateTime monthLater = now.plusMonths( 1 );

You can get the first moment of a day.

ZoneId zoneId = ZoneId.of( "America/Montreal" ); ZonedDateTime tomorrowStart = now.toLocalDate().atStartOfDay( zoneId ); // Usually time-of-day of `00:00:00.0` but not always.

If you need only a date without time-of-day and without time zone, use LocalDate. Similarly, LocalTime for time-only without date and without time zone. Usually better to stick with Instant and OffsetDateTime/ZonedDateTime as the Local… types do not represent actual moments on the timeline (no offset or time zone means they are undefined).

LocalDate localDate = LocalDate.now( zoneId ); LocalTime localTime = LocalTime.now( zoneId );
Improve this answer

1 Comment

The first question is still unanswered here
3

Comparison of Date/Time features in .NET and Java

.NET DateTime (C#) Joda DateTime (Java, deprecated) [See Note #2] Java Date
DateTime.MinValue new DateTime(Long.MIN_VALUE) new Date(Long.MIN_VALUE) [See Note #3]
DateTime.Today new DateTime().withTimeAtStartOfDay() Messy [See Note #4]
DateTime.Now new DateTime() new Date()
DateTime.MaxValue new DateTime(Long.MAX_VALUE) new Date(Long.MAX_VALUE)

Additional notes:

  1. Dealing with dates and times is messy. This table is intended to be a starting point for code migrations. The comparisons compare concepts, not exact values (e.g. .NET's minimum date/time is not the same value as Java's)
  2. Joda DateTime is the preferred date/time library for Java.
  3. See additional notes on new Date(Long.MIN_VALUE) in Java
  4. Getting start of day with Java's Date is a little more involved - see here.
  5. .NET DateTimes default to local date/time, whereas in Java they default to UTC. Make sure to consider any impact of timezones when working with dates and times.

Joda-Time Deprecated

Joda-Time is deprecated. From their web-site archive:

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.

Meaning that java.util.Date → org.joda.time.DateTime → java.time.ZonedDateTime

Giving us new mappings:

.NET DateTime (C#) java.time (formerly known as Joda-Time) Java Date
DateTime.MinValue LocalDateTime.MIN new Date(Long.MIN_VALUE)
DateTime.Today LocalDateTime.of(LocalDate.NOW, LocalTime.MIDNIGHT) (not available)
DateTime.Now LocalDateTime.now() new Date()
DateTime.UtcNow LocalDateTime.now(ZoneOffset.UTC) (not available)
DateTime.MaxValue LocalDateTime.MAX new Date(Long.MAX_VALUE)

The .NET DateTime contains:

  • date
  • time
  • and no particular information about what timezone it contains (except to day "Local", "UTC", or "Unspecified").

This means the java.time equivalent is LocalDateTime. If you want a datetime object that also carries with it an offset from UTC:

  • .NET: DateTimeOffset
  • java.time: ZonedDateTime
Improve this answer

Comments

-2

Most date manipulation should be done using the Calendar object now.

http://download.oracle.com/javase/6/docs/api/java/util/Calendar.html

Improve this answer

3 Comments

this doesn't answer his question.
@Bozho, as Chris has understood I was attempting to point him in the right direction for date manipulation with core Java.
I didn't think it was Bozho, I've read enough of your answers that you don't strike me as that petty. I admit the answer could have had much more detail but I didn't really have time.
-2

to get the current date:

Calendar calendar = Calendar.getInstance(); SimpleDateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy");

 try { System.out.println("Today: " + dateFormat.format(calendar.getTime())); } catch (Exception e) { e.printStackTrace(); }
Improve this answer

Comments

-2

Theres calendar http://download.oracle.com/javase/1.5.0/docs/api/java/util/Calendar.html

And date http://download.oracle.com/javase/1.4.2/docs/api/java/util/Date.html

Theres also simpledateformat for formatting. http://download.oracle.com/javase/1.4.2/docs/api/java/text/SimpleDateFormat.html

Improve this answer

Comments

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.