CODEWITHSUNDEEP
javascalajodatime
Abdul Mannan Ahmed
Abdul Mannan Ahmed

Reputation: 41

Parse list of dates to list string in scala

Need to format date according to yyyyMMdd below code generates a list of dates

import org.joda.time.LocalDate
import org.joda.time._

def getDates(startDate: String,endDate: String): Any = {
    val from = LocaDate.parse(startDate)
    val until = LocalDate.parse(endDate)
    val numberOfDays = Days.daysBetween(from, until).getDays()
    for (f<- 0 to numberOfDays) yield from.plusDays(f)
}

println(getDates("20200101","20200131"))

This returns -> Vector(2020-01-01,2020-01-31)

Need to convert returned Vector to List[String] in which elements are of format "yyyyMMdd"

Expected Output: List(20200101,....,20200131)

Upvotes: 1

Views: 710

Answers (1)

jwvh
jwvh

Reputation: 51271

If the getDates() input is 2 strings, and the desired output is List[String], then I don't really see any reason to use the old and outdated Joda Time library. The java.time library is more recent and feature-full.

It also offers the datesUntil() method, which does pretty much what you want, except that it returns a java.util.stream.Stream, which is a bit of a pain because the transition from Java Stream to Scala List will depend on the Scala version you're running.

Here, for example, is how you might do it in Scala 2.13.x:

import java.time.LocalDate
import java.time.format.DateTimeFormatter
import scala.jdk.StreamConverters.StreamHasToScala

def getDates(startDate:String, endDate:String):List[String] = {
  val pattern = DateTimeFormatter.ofPattern("yyyyMMdd")
  LocalDate.parse(startDate, pattern)
           .datesUntil(LocalDate.parse(endDate, pattern).plusDays(1))
           .toScala(List)
           .map(_.format(pattern))
}

You'll notice that there is no checking for valid input format, so this is for demonstration and not production-worthy code.

Upvotes: 2

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