How to automate the creation of String elements with datetime - scala

Question

This thread arises from my previous question. I need to create Seq[String] that contains paths as String elements, however now I also need to add numbers 7,8,...-22 after a date. Also I cannot use LocalDate as it was suggested in the answer to the above-cited question:
path/file_2017-May-1-7
path/file_2017-May-1-8
...
path/file_2017-May-1-22
path/file_2017-April-30-7
path/file_2017-April-30-8
...
path/file_2017-April-30-22
..
I am searching for a flexible solution. My current solution implies the manual definition of dates yyyy-MMM-dd. However it is not efficient if I need to include more than 2 dates, e.g. 10 or 100. Moreover filePathsList is currently Set[Seq[String]] and I don't know how to convert it into Seq[String].
val formatter = new SimpleDateFormat("yyyy-MMM-dd")
val currDay = Calendar.getInstance
currDay.add(Calendar.DATE, -1)
val day_1_ago = currDay.getTime
currDay.add(Calendar.DATE, -1)
val day_2_ago = currDay.getTime
val dates = Set(formatter.format(day_1_ago),formatter.format(day_2_ago))
val filePathsList = dates.map(date => {
val list: Seq.empty[String]
for (num <- 7 to 22) {
list :+ s"path/file_$date-$num" + "
}
list
})

Answer 1

Here is how I was able to achieve what you outlined, adjust the days val to configure the amount of days you care about:
import java.text.SimpleDateFormat
import java.util.Calendar
val currDay = Calendar.getInstance
val days = 5
val dates = currDay.getTime +: List.fill(days){
currDay.add(Calendar.DATE, -1)
currDay.getTime
}
val formatter = new SimpleDateFormat("yyyy-MMM-dd")
val filePathsList = for {
date <- dates
num <- 7 to 22
} yield s"path/file_${formatter.format(date)}-$num"