How to get the current date/time in Java [duplicate]
What's the best way to get the current date/time in Java?
It depends on what form of date / time you want:
-
If you want the date / time as a single numeric value, then
System.currentTimeMillis()
gives you that, expressed as the number of milliseconds after the UNIX epoch (as a Javalong
). This value is a delta from a UTC time-point, and is independent of the local time-zone1. -
If you want the date / time in a form that allows you to access the components (year, month, etc) numerically, you could use one of the following:
-
new Date()
gives you aDate
object initialized with the current date / time. The problem is that theDate
API methods are mostly flawed ... and deprecated. -
Calendar.getInstance()
gives you aCalendar
object initialized with the current date / time, using the defaultLocale
andTimeZone
. Other overloads allow you to use a specificLocale
and/orTimeZone
. Calendar works ... but the APIs are still cumbersome. -
new org.joda.time.DateTime()
gives you a Joda-time object initialized with the current date / time, using the default time zone and chronology. There are lots of other Joda alternatives ... too many to describe here. (But note that some people report that Joda time has performance issues.; e.g. https://stackoverflow.com/questions/6280829.) -
in Java 8, calling
java.time.LocalDateTime.now()
andjava.time.ZonedDateTime.now()
will give you representations2 for the current date / time.
-
Prior to Java 8, most people who know about these things recommended Joda-time as having (by far) the best Java APIs for doing things involving time point and duration calculations.
With Java 8 and later, the standard java.time
package is recommended. Joda time is now considered "obsolete", and the Joda maintainers are recommending that people migrate.3.
1 - System.currentTimeMillis()
gives the "system" time. While it is normal practice for the system clock to be set to (nominal) UTC, there will be a difference (a delta) between the local UTC clock and true UTC. The size of the delta depends on how well (and how often) the system's clock is synced with UTC.
2 - Note that LocalDateTime doesn't include a time zone. As the javadoc says: "It cannot represent an instant on the time-line without additional information such as an offset or time-zone."
3 - Note: your Java 8 code won't break if you don't migrate, but the Joda codebase may eventually stop getting bug fixes and other patches. As of 2020-02, an official "end of life" for Joda has not been announced, and the Joda APIs have not been marked as Deprecated.
(Attention: only for use with Java versions <8. For Java 8+ check other replies.)
If you just need to output a time stamp in format YYYY.MM.DD-HH.MM.SS (very frequent case) then here's the way to do it:
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(Calendar.getInstance().getTime());
If you want the current date as String, try this:
DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Date date = new Date();
System.out.println(dateFormat.format(date));
or
DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Calendar cal = Calendar.getInstance();
System.out.println(dateFormat.format(cal.getTime()));
http://www.mkyong.com/java/java-how-to-get-current-date-time-date-and-calender/