Horizontal Month Selector for Flutter

if you dont want to use package here simple code, you can customize with your own style :

import 'package:flutter/material.dart';

typedef OnHorizontalDatePickerSelected = void Function(DateTime dateTime);
typedef OnHorizontalDatePickerSubmitted = void Function(DateTime dateTime);
class HorizontalDatePicker extends StatefulWidget {
  final DateTime? initial;
  final OnHorizontalDatePickerSelected onSelected;
  final OnHorizontalDatePickerSubmitted? onSubmitted;
  const HorizontalDatePicker({Key? key, this.initial, required this.onSelected, this.onSubmitted}) : super(key: key);

  @override
  State<HorizontalDatePicker> createState() => _HorizontalDatePickerState();
}

class _HorizontalDatePickerState extends State<HorizontalDatePicker> {
  static const Map<int, String> _monthList =
    {DateTime.january: 'Jan',
      DateTime.february: 'Feb',
      DateTime.march: 'Mar',
      DateTime.april: 'Apr',
      DateTime.may: 'May',
      DateTime.june: 'Jun',
      DateTime.july: 'Jul',
      DateTime.august: 'Aug',
      DateTime.september: 'Sep',
      DateTime.october: 'Okt',
      DateTime.november: 'Nov',
      DateTime.december: 'Des'};


  late DateTime _current;

  @override
  void initState() {
    super.initState();
    _current = widget.initial ?? DateTime.now();
  }

  @override
  Widget build(BuildContext context) {
    return Row(
      mainAxisAlignment: MainAxisAlignment.spaceAround,
      children: [
        _previous(),
        _month(),
        _year(),
        _next(),
        widget.onSubmitted !=null? _button() : const SizedBox()
      ],
    );
  }

  Widget _previous() {
    return IconButton(
        onPressed: () {
          setState(() {
            _current = DateTime(_current.year, _current.month - 1);
          });
          widget.onSelected(_current);
        },
        icon: const Icon(Icons.arrow_back_ios_sharp));
  }

  Widget _next() {
    return IconButton(
        onPressed: () {
          setState(() {
            _current = DateTime(_current.year, _current.month + 1);
          });
          widget.onSelected(_current);
        },
        icon: const Icon(Icons.arrow_forward_ios_sharp));
  }

  Widget _month() {
    return Padding(
      padding: const EdgeInsets.all(10.0),
      child: Text('${_monthList[_current.month]}'),
    );
  }

  Widget _year() {
    return Padding(
      padding: const EdgeInsets.all(10.0),
      child: Text('${_current.year}'),
    );
  }

  Widget _button(){
    return Row(
      children: [
        TextButton(onPressed: (){
          widget.onSubmitted!(_current);
        }, child: const Text("Select"))
      ],
    );
  }
}

use it anywhere you want :

Scaffold(
        body: HorizontalDatePicker(
          onSelected: (DateTime time){
            print(time);
          },
          onSubmitted: (DateTime time){
            print(time);
          },
        ),
      ),