I have a list of Dates in format : dd-MM-yyyy
val tripDates = [03-03-2022, 05-03-2002, 23-02-2022]
Now I need to map this list to have not repeatable dates in format only : MM-yyyy
I have tryed to do this as a map:
val calendar = Calendar.getInstance()
val myFormat = "MM-yyyy"
val dateFormat = SimpleDateFormat(myFormat, Locale.US)
val formattedTrips = tripDates.map {
calendar.time = it
val month = calendar.get(Calendar.MONTH+1).toString()
val year = calendar.get(Calendar.YEAR).toString()
val monthAndYear = "$month-$year"
dateFormat.parse(monthAndYear)
}
But It doesnt work. I cannot make a new map. Any ideas?
If I understood your question correctly, you want to read dates (as string) and output them to another format (as string).
We need two formatters, one to convert the string (in a given pattern) to date and another to convert the date back to string (in a different pattern).
Java 7
import java.text.SimpleDateFormat
val fullDatePattern = "dd-MM-yyyy"
val monthYearPattern = "MM-yyyy"
val fullDateFormatter = SimpleDateFormat(fullDatePattern)
val monthYearFormatter = SimpleDateFormat(monthYearPattern)
val dates = listOf(
"03-03-2022",
"05-03-2002",
"23-02-2022",
)
dates.map { dateString ->
monthYearFormatter.format(fullDateFormatter.parse(dateString))
}
I think it's worth mentioning that SimpleDateFormat is not thread-safe, so be careful.
Java 8+
import java.time.LocalDate
import java.time.format.DateTimeFormatter
val fullDatePattern = "dd-MM-yyyy"
val monthYearPattern = "MM-yyyy"
val fullDateFormatter = DateTimeFormatter.ofPattern(fullDatePattern)
val monthYearFormatter = DateTimeFormatter.ofPattern(monthYearPattern)
val dates = listOf(
"03-03-2022",
"05-03-2002",
"23-02-2022",
)
dates.map { dateString ->
LocalDate
.parse(dateString, fullDateFormatter)
.format(monthYearFormatter)
}
Output for both examples above: [03-2022, 03-2002, 02-2022]
And if you want to remove duplicated dates, you can use the function distinct.