How to get the week number from a date string with 2 character output

Question

I can use the below code to get the output as weekNumber: Int = 1 . But my use case require the output as weekNumber: String= 01 . What should be the best efficient way to do approach this?

import java.time.format.DateTimeFormatter
import java.time.temporal.WeekFields
import java.util.Locale
import java.time.LocalDate

var dateRangeFrom = "20200101"
var date :java.time.LocalDate = LocalDate.parse(dateRangeFrom,DateTimeFormatter.ofPattern("yyyyMMdd"))

var weekFields :WeekFields =  WeekFields.of(Locale.getDefault());
var weekNumber :Int = date.get(weekFields.weekOfWeekBasedYear());

Output - weekNumber: Int = 1

Answer 1

You can use DateTimeFormatter with the pattern ww :

var weekFormat = DateTimeFormatter.ofPattern("ww");
var weekNumber = weekFormat.format(date);

"w" is the week of year, "ww" is week of year with two digits (zero fill). You can see the list of formatting codes in the API documentation. https://docs.oracle.com/javase/10/docs/api/java/time/format/DateTimeFormatter.html