How to get the start and end of a calendar week as LocalDateTime (java 8)

Question

I want to transform the following String:

private String cw = "35/19" 

into 2 dates.

The start date can be formatted with:

private final DateTimeFormatter startOfWeekFormat = new DateTimeFormatterBuilder()
   .appendPattern("ww/YY")
   .parseDefaulting(WeekFields.ISO.dayOfWeek(), 1)
   .toFormatter();

which when called returns: 26.08.2019

LocalDate.parse(cw, startOfWeekFormat).atStartOfDay();

But I struggle with the end of the week which is basically the start of the next week "36/19".

I tried to add plus 8 days, but that throws an exception:

private final DateTimeFormatter endOfWeekFormat = new DateTimeFormatterBuilder()
    .appendPattern("ww/YY")
    .parseDefaulting(WeekFields.ISO.dayOfWeek(), 8)
    .toFormatter();

Answer 1

LocalDateTime ldt=LocalDate.parse(cw, startOfWeekFormat)
                    .atStartOfDay()
                    .with(TemporalAdjusters.next(DayOfWeek.MONDAY));

Demo:

import java.time.DayOfWeek;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeFormatterBuilder;
import java.time.temporal.TemporalAdjusters;
import java.time.temporal.WeekFields;

public class Main {
    public static void main(String[] args) {
        String cw = "35/19";
        final DateTimeFormatter startOfWeekFormat = new DateTimeFormatterBuilder()
                                            .appendPattern("ww/YY")
                                            .parseDefaulting(WeekFields.ISO.dayOfWeek(), 1)
                                            .toFormatter();
        
        LocalDateTime ldt=LocalDate.parse(cw, startOfWeekFormat)
                            .atStartOfDay()
                            .with(TemporalAdjusters.next(DayOfWeek.MONDAY));
        System.out.println(ldt);
    }
}

Output:

2019-09-02T00:00