What argument should i give?-CodePudding

In the application, the home page is ResultScreen, which displays the entered data. If they are not there, then when you click on the button, we go to the screen with the input. When I enter text into the input and click on the Display Result button, the data should be substituted into the text field on the first screen. I implemented such functionality, but I don’t understand what argument I should substitute in main.dart. Tell me please Text Screen:

import 'package:flutter/material.dart';
import 'package:flutter_application_1/screens/result_screen.dart';

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

  @override
  State<TextScreen> createState() => _TextScreenState();
}

class _TextScreenState extends State<TextScreen> {
  TextEditingController textController = TextEditingController();

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Enter data'),
      ),
      body: Padding(
          padding: const EdgeInsets.symmetric(horizontal: 16.0),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              TextField(
                controller: textController,
                decoration: InputDecoration(labelText: 'Message'),
              ),
              const SizedBox(
                height: 20,
              ),
              ElevatedButton(
                  onPressed: () {
                    Navigator.push(
                        context,
                        MaterialPageRoute(
                            builder: (context) =>
                                ResultScreen(textController.text)));
                  },
                  child: Text('Display result'))
            ],
          )),
    );
  }
}

Result Screen:

import 'package:flutter/material.dart';
import 'package:flutter_application_1/screens/text_screen.dart';

class ResultScreen extends StatefulWidget {
  final String valueText;
  ResultScreen(this.valueText);

  @override
  State<ResultScreen> createState() => _ResultScreenState();
}

class _ResultScreenState extends State<ResultScreen> {
  // navigation to text_screen
  void _buttonNav() {
    Navigator.push(
        context, MaterialPageRoute(builder: (context) => const TextScreen()));
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Results'),
      ),
      body: Center(
          child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          ElevatedButton(
              onPressed: _buttonNav, child: const Text('Enter data')),
          const SizedBox(
            height: 50,
          ),
          Text(valueText),
          const SizedBox(
            height: 20,
          ),
        ],
      )),
    );
  }
}

Main.dart:

import 'package:flutter/material.dart';
import 'package:flutter_application_1/screens/result_screen.dart';

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

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: ResultScreen(),
    );
  }
}

CodePudding user response：

Use the following code. What is does is, when we enter the first screen i.e. ResultScreen, we pass an empty value for the first time.

Use this in main.dart

home: ResultScreen(''),

And as you are using statefull widget for ResultScreen, you need to use widget.valueText to access it like:

Text(widget.valueText),