Flutter Day

main.dart

import 'dart:async';

import 'package:flutter/material.dart';

void main() {
  runApp(FlagCircle());
}

class FlagCircle extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return _FlagCircleState();
  }
}

class _FlagCircleState extends State<FlagCircle> {
  static const _countries = [
    'au',
    'nz',
    'us',
    'fi',
    'ua',
    'se',
    'de',
    'dk',
    'fr',
    'ru',
    'it',
    'be',
    'sg',
    'no',
    'nl',
    'ch',
    'at',
    'gb',
    'ee',
    'mc',
  ];

  List<String> countryCodes;

  @override
  void initState() {
    super.initState();
    init();
  }

  void init() {
    _prepList(_countries);
    Timer.periodic(Duration(milliseconds: 250), (timer) {
      setState(() {
        if (countryCodes.length == 1) {
          timer.cancel();
        }
        _prepList(countryCodes);
      });
    });
  }

  void _prepList(List<String> prevList) {
    countryCodes = prevList.sublist(1)..shuffle();
    countryCodes[0] = 'au';
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        appBar: AppBar(title: Text("Flutter Day!")),
        body: Center(
          child: Container(
            width: 80,
            child: ListView.builder(
              shrinkWrap: true,
              itemCount: countryCodes.length,
              itemBuilder: (_, i) {
                return _buildFlag(countryCodes[i]);
              },
            ),
          ),
        ),
      ),
    );
  }

  Widget _buildFlag(String countryCode) {
    return Padding(
      padding: EdgeInsets.fromLTRB(0, 10, 0, 10),
      child: FlatButton(
          onPressed: () => setState(() {
                init();
              }),
          child: Image.network(
              'https://www.countryflags.io/$countryCode/flat/64.png')),
    );
  }
}