how to receive data in constructor again in flutter?-CodePudding

I have a button in a page. and a class named MySdClass. In my main class i have a constructor that receive some data from MySdClass. i want wen user click on button the constructor of that page receive data from MySdClass again. The code I imagine in my mind does not work:

import 'package:flutter/material.dart';
import 'package:./SdClass.dart';

void main(){
runApp(MainClass(inputData: MySdClass.data,));
}

class MainClass extends StatelessWidget {
final String data;
const MainClass({Key? key, required this.data}) : super(key: key);

@override
Widget build(BuildContext context) {
return Row(
  children: [
    Container(
      const Text(this.widget.data),
    ),
    ElevatedButton(onPressed: (){//what should be here?}, child: const 
Text('next')),
     ],
   );
  }
 }

CodePudding user response：

void main(){
  runApp(MainClass(inputData: MySdClass.data, onPressed:(){
  "Perform some action and you can send data again through this contructor"
});
 }

 class MainClass extends StatelessWidget {
 final String data;
 void Function() onPressed;
 MainClass({Key? key, required this.data,required this.onPressed}) : super(key: key);

  @override
 Widget build(BuildContext context) {
 return Row(
  children: [
Container(
  const Text(this.widget.data),
),
ElevatedButton(onPressed: onPressed, child: const 
 Text('next')),
 ],
  );
 }
     }

CodePudding user response：

you could set variable and use it like this:

class MainClass extends StatefulWidget {
  final String data;

  MainClass({Key key, @required this.data}) : super(key: key);

  @override
  State<MainClass> createState() => _MainClassState();
}

class _MainClassState extends State<MainClass> {
  String _data;
  @override
  void initState() {
    super.initState();
    _data = widget.data;
  }

  @override
  Widget build(BuildContext context) {
    return Row(
      children: [
        Container(
          child: Text(this.widget.data),
        ),
        ElevatedButton(
            onPressed: () {
              setState(() {
                _data = MySdClass.data;
              });
              
            },
            child: const Text('next')),
      ],
    );
  }
}