问题
What's the standard way to work with dates and times in Scala? Should I use Java types such as java.util.Date or there are native Scala alternatives?
回答1:
From Java SE 8 onwards, users are asked to migrate to java.time (JSR-310). There are efforts on creating scala libraries wrapping java.time for scala such as scala-time. If targeting lower than SE 8 use one of the below. Also see Why JSR-310 isn't Joda-Time
A new Scala wrapper for Joda Time. This project forked from scala-time since it seems that scala-time is no longer maintained.
import com.github.nscala_time.time.Imports._
DateTime.now // returns org.joda.time.DateTime = 2009-04-27T13:25:42.659-07:00
DateTime.now.hour(2).minute(45).second(10) // returns org.joda.time.DateTime = 2009-04-27T02:45:10.313-07:00
DateTime.now + 2.months // returns org.joda.time.DateTime = 2009-06-27T13:25:59.195-07:00
DateTime.nextMonth < DateTime.now + 2.months // returns Boolean = true
DateTime.now to DateTime.tomorrow // return org.joda.time.Interval = > 2009-04-27T13:47:14.840/2009-04-28T13:47:14.840
(DateTime.now to DateTime.nextSecond).millis // returns Long = 1000
2.hours + 45.minutes + 10.seconds
// returns com.github.nscala_time.time.DurationBuilder
// (can be used as a Duration or as a Period)
(2.hours + 45.minutes + 10.seconds).millis
// returns Long = 9910000
2.months + 3.days
// returns Period
Joda Time is a good Java library, there is a Scala wrapper / implicit conversion library avaliable for Joda Time at scala-time created by Jorge Ortiz. (Note implicits have a performance hit, but it depends on what you do if you will notice. And if you run into a performance problem you can just revert to the Joda interface)
From the README:
USAGE:
import org.scala_tools.time.Imports._
DateTime.now
// returns org.joda.time.DateTime = 2009-04-27T13:25:42.659-07:00
DateTime.now.hour(2).minute(45).second(10)
// returns org.joda.time.DateTime = 2009-04-27T02:45:10.313-07:00
DateTime.now + 2.months
// returns org.joda.time.DateTime = 2009-06-27T13:25:59.195-07:00
DateTime.nextMonth < DateTime.now + 2.months
// returns Boolean = true
DateTime.now to DateTime.tomorrow
// return org.joda.time.Interval =
// 2009-04-27T13:47:14.840/2009-04-28T13:47:14.840
(DateTime.now to DateTime.nextSecond).millis
// returns Long = 1000
2.hours + 45.minutes + 10.seconds
// returns org.scala_tools.time.DurationBuilder
// (can be used as a Duration or as a Period)
(2.hours + 45.minutes + 10.seconds).millis
// returns Long = 9910000
2.months + 3.days
// returns Period
回答2:
If you are using Java 8, then there is no need to use nscala anymore. The Joda-Time library has been moved into Java 8 under the java.time package (JSR-310). Just import that package into your Scala project.
回答3:
There is no standard way to work with dates in Scala. The options available are:
- Use java.time (if you are using Java 8) since it has the best of JODA time built into it. No implicits.
- Use nscala-time.
- Lamma date library (relatively new library on the scene)
I would avoid using java.util.Date due to the well-documented issues surrounding it.
回答4:
MOTIVATION:
The Java Date and Calendar libraries are largely inadequate. They are mutable, not thread-safe, and very inconvenient to use.
The Joda Time library is a great replacement for Java's Date and Calendar classes. They're immutable by default, have a much richer and nicer API, and can easily be converted to Java's Date and Calendar classes when necessary.
This project provides a thin layer of convenience around the Joda Time libraries, making them more idiomatic to use within Scala.
(copied from https://github.com/jorgeortiz85/scala-time)
回答5:
Everyone uses JodaTime, these Scala helper/wrapper libraries may need re-compilation with new versions of Scala. Jodatime is the only time library that's been around for a long time, and is stable and works reliably with every version of Scala.
来源：https://stackoverflow.com/questions/3614380/whats-the-standard-way-to-work-with-dates-and-times-in-scala-should-i-use-java