flutter flex layout example

main.dart

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  final String title;

  const MyHomePage({
    Key? key,
    required this.title,
  }) : super(key: key);

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  Icon _getIcon(state) {
    switch (state) {
      case 0:
        return const Icon(Icons.remove);
      case 1:
        return const Icon(Icons.play_arrow);
      case 2:
        return const Icon(Icons.warning);
      default:
        return const Icon(Icons.done);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Flex(
        direction: Axis.horizontal,
        mainAxisAlignment: MainAxisAlignment.spaceAround,
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          Expanded(
            flex: 1,
            child: Container(
              padding: const EdgeInsets.all(16.0),
              child: ListView.builder(
                itemBuilder: (context, index) {
                  return Wrap(
                    crossAxisAlignment: WrapCrossAlignment.center,
                    children: [
                      _getIcon(index % 4),
                      Text('item$index'),
                    ],
                  );
                },
                itemCount: 100,
              ),
            ),
          ),
          Expanded(
            flex: 1,
            child: Container(
              padding: const EdgeInsets.all(16.0),
              child: Flex(
                direction: Axis.vertical,
                children: [
                  const Expanded(
                    child: Text('right1'),
                  ),
                  SizedBox(
                    height: 20,
                    child: ElevatedButton(
                      child: const Text('button1'),
                      onPressed: () {
                        print('button1');
                      },
                    ),
                  ),
                ],
              ),
            ),
          ),
        ],
      ),
    );
  }
}