Week list not give me correct out put

My code :

1. Select 24 date

2. they print 31/07 - 31/07

3. not print like this 31/07 - 06/08

import 'package:flutter/material.dart';
import 'package:intl/intl.dart';
class WeekList extends StatefulWidget {
const WeekList({super.key});
@override
State<WeekList> createState() => _WeekListState();
}
class _WeekListState extends State<WeekList> {
@override
Widget build(BuildContext context) {
DateTime currentDate = DateTime.now();
DateTime startOfWeek = getStartOfWeek(currentDate);
List<String> weekDateRange = generateWeekDateRange(startOfWeek, 5); // 5 weeks display karein
return MaterialApp(
home: Scaffold(
appBar: AppBar(
title: const Text('Date Range List'),
),
body: ListView.builder(
itemCount: weekDateRange.length,
itemBuilder: (context, index) {
String dateRange = weekDateRange[index];
bool isSelected = isDateRangeSelected(dateRange, currentDate);
return ListTile(
title: Text(
dateRange,
style: TextStyle(
fontWeight: isSelected ? FontWeight.bold : FontWeight.normal,
),
),
);
},
),
),
);
}
}
DateTime getStartOfWeek(DateTime date) {
return date.subtract(Duration(days: date.weekday - 1));
}
List<String> generateWeekDateRange(DateTime startOfWeek, int numberOfWeeks) {
List<String> weekList = [];
for (int i = 0; i < numberOfWeeks; i++) {
DateTime endDate = startOfWeek.add(const Duration(days: 6));
if (endDate.day <= 7) {
// Check if endDate is on or before the 7th day of the month
DateTime nextMonth = DateTime(startOfWeek.year, startOfWeek.month + 1, 1);
endDate = nextMonth.subtract(const Duration(days: 1));
}
if (endDate.isAfter(DateTime(startOfWeek.year, startOfWeek.month, startOfWeek.day + 6))) {
// Check if endDate is in the next month
endDate = DateTime(startOfWeek.year, startOfWeek.month, startOfWeek.day + 6);
}
String formattedDateRange =
'${DateFormat('dd/MM').format(startOfWeek)} - ${DateFormat('dd/MM').format(endDate)}';
weekList.add(formattedDateRange);
// Move the startOfWeek to the next week
startOfWeek = endDate.add(const Duration(days: 1));
}
return weekList;
}
bool isDateRangeSelected(String dateRange, DateTime currentDate) {
List<String> parts = dateRange.split(' - ');
DateTime startDate = DateFormat('dd/MM').parse(parts[0]);
DateTime endDate = DateFormat('dd/MM').parse(parts[1]);
return currentDate.isAfter(startDate) && currentDate.isBefore(endDate.add(const Duration(days: 1)));
}

Current output:

I/flutter (30371): 01/08 - 07/08
I/flutter (30371): 08/08 - 14/08
I/flutter (30371): 15/08 - 21/08
I/flutter (30371): 24/07 - 30/07
I/flutter (30371): 31/07 - 31/07

i want to print like this:

24/07 - 30-07  
31/07 -  06/08  
07/08 - 13/08  
14/08 - 20/08

You most likely hit into the issue of handling daylight summer time (DST). DateTime in Dart are default your local timezone which often have the concept of DST. When you use add/sub on DateTime, you provide a Duration object which converts all units into e.g. milliseconds. So when adding days, it will convert each day to 24 hour and so on.

But because DST allows days to be sometimes 25 hours and 23 hours long, the adding of days in Dart does often give these problems.

The solution is often to use UTC as timezone instead since this is a fixed timezone without DST. So when you want current time, use DateTime.timestamp() instead to get a UTC version of DateTime. And when you create new DateTime objects, make sure to use the DateTime.utc() constructor instead of DateTime.

Read more about this in the documentation of DateTime: https://api.dart.dev/stable/3.0.6/dart-core/DateTime-class.html

I can also see your generateWeekDateRange method are a lot more complicated than needed for the output you want.

Example of how I think your code could be fixed where I have also simplified generateWeekDateRange. I don't use Flutter myself so I have not tested it:

import 'package:flutter/material.dart';
import 'package:intl/intl.dart';

class WeekList extends StatefulWidget {
  const WeekList({super.key});

  @override
  State<WeekList> createState() => _WeekListState();
}

class _WeekListState extends State<WeekList> {
  @override
  Widget build(BuildContext context) {
    DateTime currentDate = DateTime.timestamp();
    DateTime startOfWeek = getStartOfWeek(currentDate);

    List<String> weekDateRange =
        generateWeekDateRange(startOfWeek, 5); // 5 weeks display karein

    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Date Range List'),
        ),
        body: ListView.builder(
          itemCount: weekDateRange.length,
          itemBuilder: (context, index) {
            String dateRange = weekDateRange[index];
            bool isSelected = isDateRangeSelected(dateRange, currentDate);
            return ListTile(
              title: Text(
                dateRange,
                style: TextStyle(
                  fontWeight: isSelected ? FontWeight.bold : FontWeight.normal,
                ),
              ),
            );
          },
        ),
      ),
    );
  }
}

DateTime getStartOfWeek(DateTime date) {
  return date.subtract(Duration(days: date.weekday - 1));
}

List<String> generateWeekDateRange(DateTime startOfWeek, int numberOfWeeks) {
  List<String> weekList = [];
  for (int i = 0; i < numberOfWeeks; i++) {
    DateTime endDate = startOfWeek.add(const Duration(days: 6));

    String formattedDateRange =
        '${DateFormat('dd/MM').format(startOfWeek)} - ${DateFormat('dd/MM').format(endDate)}';
    weekList.add(formattedDateRange);

    // Move the startOfWeek to the next week
    startOfWeek = endDate.add(const Duration(days: 1));
  }
  return weekList;
}

bool isDateRangeSelected(String dateRange, DateTime currentDate) {
  List<String> parts = dateRange.split(' - ');
  DateTime startDate = DateFormat('dd/MM').parseUtc(parts[0]);
  DateTime endDate = DateFormat('dd/MM').parseUtc(parts[1]);
  return currentDate.isAfter(startDate) &&
      currentDate.isBefore(endDate.add(const Duration(days: 1)));
}