Flutter AppにTextFieldを追加してみた

import 'package:flutter/material.dart';
import 'package:flutter_gen/gen_l10n/app_localizations.dart';
import 'package:my_app_01/my_first_page.dart';
import 'package:my_app_01/my_home_page.dart';

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      localizationsDelegates: AppLocalizations.localizationsDelegates,
      supportedLocales: AppLocalizations.supportedLocales,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: DefaultTabController(
        length: 3,
        child: Scaffold(
          appBar: AppBar(
            bottom: const TabBar(
              tabs: [
                Tab(icon: Icon(Icons.looks_one)),
                Tab(icon: Icon(Icons.looks_two)),
                Tab(icon: Icon(Icons.looks_3)),
              ],
            ),
            title: const Text('Tabs Demo'),
          ),
          body: const TabBarView(
            children: [
              MyFirstPage(),
              Icon(Icons.looks_two),
              MyHomePage(title: 'Flutter Demo Home Page'),
            ],
          ),
        ),
      ),
    );
  }
}

import 'package:flutter/material.dart';
import 'package:flutter_gen/gen_l10n/app_localizations.dart';

class MyFirstPage extends StatefulWidget {
  const MyFirstPage({Key? key}) : super(key: key);

  @override
  State<MyFirstPage> createState() => _MyFirstPageState();
}

class _MyFirstPageState extends State<MyFirstPage> {
  late TextEditingController _controller;

  @override
  void initState() {
    super.initState();
    _controller = TextEditingController();
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(AppLocalizations.of(context)!.firstPage),
      ),
      body: Container(
        padding: const EdgeInsets.all(8),
        child: Column(
          children: <Widget>[
            const Text('First Page'),
            TextField(
              controller: _controller,
              onSubmitted: (String value) async {
                await showDialog<void>(
                  context: context,
                  builder: (BuildContext context) {
                    return AlertDialog(
                      title: const Text('Title'),
                      content: Text(
                          '"$value", which has length ${value.characters.length}.'),
                      actions: <Widget>[
                        TextButton(
                          onPressed: () {
                            Navigator.pop(context);
                          },
                          child: const Text('OK'),
                        ),
                      ],
                    );
                  },
                );
              },
            ),
          ],
        ),
      ),
    );
  }
}

{
    "helloWorld": "Hello World!",
    "@helloWorld": {
      "description": "The conventional newborn programmer greeting"
    },
    "firstPage": "First Page","@firstPage": {"description": "First Page Title"}
}

{
    "helloWorld": "こんにちは。",
    "firstPage": "最初のページ"
}