datetime datatype in java

Question

Which data type can I use in Java to hold the current date as well as time?. I want to store the datetime in a db as well as having a field in the java bean to hold that.

is it java.util.Date ?

score 26 · Answer 1 · edited Oct 21 '13 at 15:00

java.util.Date represents an instant in time, with no reference to a particular time zone or calendar system. It does hold both date and time though - it's basically a number of milliseconds since the Unix epoch.

Alternatively you can use java.util.Calendar which does know about both of those things.

Personally I would strongly recommend you use Joda Time which is a much richer date/time API. It allows you to express your data much more clearly, with types for "just dates", "just local times", "local date/time", "instant", "date/time with time zone" etc. Most of the types are also immutable, which is a huge benefit in terms of code clarity.

My bad, got into the wrong doc. My comment is obviously misleading, I will delete it. — Autumn, Apr 13 '16 at 17:05

score 12 · Answer 2 · edited Jun 29 '11 at 06:01

12

import java.util.Date;
import java.text.DateFormat;
import java.text.SimpleDateFormat;

private String getDateTime() {
    DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
    Date date = new Date();
    return dateFormat.format(date);
}

edited Jun 29 '11 at 06:01

Brad Mace

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answered Jun 29 '11 at 05:59

Rupok

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can i mapp it to timestamp in db(mysql)? – akshay Jun 29 '11 at 06:27
yes you can map time-stamp in db. http://www.roseindia.net/jdbc/jdbc-mysql/mapping-mysql-data-types-in-java.shtml – Rupok Jun 29 '11 at 06:36

score 6 · Answer 3 · answered Apr 12 '16 at 06:15

java.time

The java.time framework built into Java 8 and later supplants both the old date-time classes bundled with the earliest versions of Java and the Joda-Time library. The java.time classes have been back-ported to Java 6 & 7 and to Android.

The Instant class represents a moment on the timeline in UTC with a resolution of nanoseconds.

Instant instant = Instant.now();

Apply an offset-from-UTC (a number of hours and possible minutes and seconds) to get an OffsetDateTime.

ZoneOffset offset = ZoneOffset.of( "-04:00" );
OffsetDateTime odt = OffsetDateTime.ofInstant( instant , offset );

Better yet is applying a full time zone which is an offset plus a set of rules for handling anomalies such as Daylight Saving Time (DST).

ZoneId zoneId = ZoneId.of( "America/Montreal" );
ZonedDateTime zdt = ZonedDateTime.ofInstant( instant , zoneId );

Database

Hopefully the JDBC drivers will be updated to work directly with the java.time classes. Until then we must use the java.sql classes to move date-time values to/from the database. But limit your use of the java.sql classes to the chore of database transit. Do not use them for business logic. As part of the old date-time classes they are poorly designed, confusing, and troublesome.

Use new methods added to the old classes to convert to/from java.time. Look for to… and valueOf methods.

Use the java.sql.Timestamp class for date-time values.

java.sql.Timestamp ts = java.sql.Timestamp.valueOf( instant );

And going the other direction…

Instant instant = ts.toInstant();

For date-time data you virtually always want the TIMESTAMP WITH TIME ZONE data type rather than WITHOUT when designing your table columns in your database.

score 3 · Answer 4 · edited May 23 '17 at 12:17

3

+1 the recommendation for Joda-time. If you plan on doing anything more than a simple Hello World example, I suggest reading this:

Daylight saving time and time zone best practices

edited May 23 '17 at 12:17

Community

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answered Jun 29 '11 at 06:01

nogridbag

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score 1 · Answer 5 · edited Mar 20 '16 at 23:28

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I used this import:

import java.util.Date;

And declared my variable like this:

Date studentEnrollementDate;

edited Mar 20 '16 at 23:28

Tim

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answered Mar 29 '15 at 19:44

dmiadan

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score 1 · Answer 6 · answered Apr 12 '16 at 03:09

1

Since Java 8, it seems like the java.time standard library is the way to go. From Joda time web page:

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.

Back to your question. Were you to use Java 8, I think you want LocalDateTime. Because it contains the date and time-of-the-day, but is unaware of time zone or any reference point in time such as the unix epoch.

answered Apr 12 '16 at 03:09

Tarrasch

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Right about using java.time but wrong about using `LocalDateTime`. Because it has no time zone or offset-from-UTC, it has no real meaning. It is not a moment on the timeline. Rarely needed in business apps. Instant, OffsetDateTime, and ZonedDateTime are all used to represent a moment on the timeline. – Basil Bourque Apr 12 '16 at 05:54
@BasilBourque Yes that's a good rephrasing. Though the question at hand wasn't really specific enough to say what is right or wrong. – Tarrasch Apr 12 '16 at 07:31
Agreed the Question is not clear, and rather anemic, lacking details. But it does say “current” date and time which almost certainly should be zoned. – Basil Bourque Apr 12 '16 at 15:59

score 1 · Answer 7 · answered Jun 29 '11 at 06:06

1

Depends on the RDBMS or even the JDBC driver.

Most of the times you can use java.sql.Timestamp most of the times along with a prepared statement:

pstmt.setTimestamp( index, new Timestamp( yourJavaUtilDateInstance.getTime() );

answered Jun 29 '11 at 06:06

OscarRyz

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Srikanth Venkatesh · Answer 8 · 2011-06-29T06:11:07.320

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You can use Calendar.

     Calendar rightNow = Calendar.getInstance();

Calendar

Date4j alternative to Date, Calendar, and related Java classes

edited Jun 29 '11 at 06:11

answered Jun 29 '11 at 06:01

Srikanth Venkatesh

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datetime datatype in java

8 Answers8

java.time

Database