YearWeek.java

import java.time.*;
import java.time.format.*;
import java.time.temporal.ChronoField;
public class YearWeek {

  public static void main(String[] args){
    for(int week = 1; week < 53; week++){
      dbYearWeekToDateRange("2023%02d".formatted(week));
    }
  }

  public static void formatYearWeek(){
    LocalDate date = LocalDate.of(2023, 6, 16);
    int weekOfYear = date.get(ChronoField.ALIGNED_WEEK_OF_YEAR);
    print(weekOfYear);

    final String yearWeek = "202324";
    dbYearWeekToDateRange(yearWeek);

    final LocalDate janFirst = LocalDate.of(2022, 1, 1);
    print(janFirst + " has day of week of " + janFirst.get(ChronoField.ALIGNED_WEEK_OF_YEAR));
  }

  public static void dbYearWeekToDateRange(final String yearWeek){
    final String year = yearWeek.substring(0, 4);
    final String week = yearWeek.substring(4);
    final int day = 1;
    String pattern = "%s-W%s-%s".formatted(year, week, day);
    print("Pattern to be parsed is  " + pattern);
    LocalDate parsed = LocalDate.parse(pattern, DateTimeFormatter.ISO_WEEK_DATE);
    final int startOfWeekOffset = 1;
    LocalDate start = parsed.plusDays(-startOfWeekOffset);
    LocalDate end = parsed.plusDays(6 - startOfWeekOffset);
    print("Date range for week %s:\n\t [ %s - %s ]\n".formatted(pattern,
                  df(start),
                  df(end)));
  }

  public static void print(Object o){
    System.out.println(o);
  }

  public static String df(LocalDate date){
    DateTimeFormatter f = DateTimeFormatter.ofPattern("YYYY-MMMM-dd EEEE");
    return f.format(date);
  }
}