Find dates between two dates scala - scala

Question

I am trying to extract dates between two dates.
If my input is:
start date: 2020_04_02
end date: 2020_06_02
Output should be:
List("2020_04_02","2020_04_03", "2020_04_04", "2020_04_05", "2020_04_06")
So far i have tried:
val beginDate = LocalDate.parse(startDate, formatted)
val lastDate = LocalDate.parse(endDate, formatted)
beginDate.datesUntil(lastDate.plusDays(1))
.iterator()
.asScala
.map(date => formatter.format(date))
.toList
import java.time.format.DateTimeFormatter
private def formatter = DateTimeFormatter.ofPattern("yyyy_MM_dd")
But i think it could be done even in a more refined way

Answer 1

I'm not super proud of this, but I've done it this way before:
import java.time.LocalDate
val start = LocalDate.of(2020,1,1).toEpochDay
val end = LocalDate.of(2020,12,31).toEpochDay
val dates = (start to end).map(LocalDate.ofEpochDay(_).toString).toArray
You end up with:
dates: Array[String] = Array(2020-01-01, 2020-01-02, ..., 2020-12-31)

Answer 2

What you are doing is correct but your end date is not matching what you are expecting:
import java.time.format.DateTimeFormatter
import java.time.LocalDate
import scala.jdk.CollectionConverters._
private def formatter = DateTimeFormatter.ofPattern("yyyy_MM_dd")
val startDate = "2020_04_02"
val endDate1 = "2020_04_06" // "2020_06_02"
val endDate2 = "2020_06_02"
val beginDate = LocalDate.parse(startDate, formatter)
val lastDate1 = LocalDate.parse(endDate1, formatter)
val lastDate2 = LocalDate.parse(endDate2, formatter)
val res1 = beginDate.datesUntil(lastDate1.plusDays(1)).iterator().asScala.map(date => formatter.format(date)).toList
val res2 = beginDate.datesUntil(lastDate2.plusDays(1)).iterator().asScala.map(date => formatter.format(date)).toList
println(res1) // List(2020_04_02, 2020_04_03, 2020_04_04, 2020_04_05, 2020_04_06)
println(res2) // List(2020_04_02, 2020_04_03, 2020_04_04, 2020_04_05, 2020_04_06 ... 2020_05_31, 2020_06_01, 2020_06_02)

Answer 3

This function will return List[String].
import java.time.format.DateTimeFormatter
import java.time.LocalDate
val dt1 = "2020_04_02"
val dt2 = "2020_04_06"
def DatesBetween(startDate: String,endDate: String) : List[String] = {
def ConvertToFormat = DateTimeFormatter.ofPattern("yyyy_MM_dd")
val sdate = LocalDate.parse(startDate,ConvertToFormat)
val edate = LocalDate.parse(endDate,ConvertToFormat)
val DateRange = sdate.toEpochDay.until(edate.plusDays(1).toEpochDay).map(LocalDate.ofEpochDay).toList
val ListofDateRange = DateRange.map(date => ConvertToFormat.format(date)).toList
ListofDateRange
}
println(DatesBetween(dt1,dt2))