navigation

main.dart

import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends MaterialApp {
  const MyApp({Key? key}) : super(home: const TextPage(), key: key);
}

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

  @override
  _TextPageState createState() => _TextPageState();
}

class _TextPageState extends State<TextPage> {
  String _text = '';

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: const Text('Navigation app'),
          actions: [
            Row(
              children: [
                const Text('Next Page', style: TextStyle(fontSize: 20)),
                const SizedBox(width: 10),
                IconButton(
                  icon: const Icon(Icons.keyboard_arrow_right),
                  onPressed: () {
                    Navigator.push(
                        context,
                        MaterialPageRoute(
                            builder: (context) => TextInputPage(
                                  callback: (value) =>
                                      setState(() => _text = value),
                                )));
                  },
                ),
                const SizedBox(width: 50),
              ],
            )
          ],
        ),
        body: Center(
            child: Text(
          _text,
          style: const TextStyle(fontSize: 20),
        )));
  }
}

class TextInputPage extends StatelessWidget {
  const TextInputPage({Key? key, required this.callback}) : super(key: key);

  final Function(String val) callback;
  static TextEditingController controller = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(title: const Text('Text Page')),
        body: Center(
          child: Padding(
            padding: const EdgeInsets.all(100),
            child: TextField(
              controller: controller,
              onChanged: (v) {
                callback(controller.text);
              },
              decoration: const InputDecoration(
                  border: OutlineInputBorder(), labelText: 'Enter text'),
            ),
          ),
        ));
  }
}