Flutter setState to another class?

Question

I have a root class RootPage which is a StatefulWidget which is always in view. I would like to change the body in RootPage

Answer 1

This was a tricky question but I got a solution for this question I to faced this problem so many times. So let's first solve your problem. And this is the solution for your code

Lets first save this file with a name feedPage.dart

`import 'package:flutter/material.dart';
class FeedPage extends StatefulWidget {
  @override
  _feedPageState createState() => new _feedPageState();
}
class _feedPageState extends State {

  @override
  Widget build(BuildContext context) {
    return new FlatButton(
      onPressed: () {
        setState(() {
          //change the currentPage in RootPage so it switches FeedPage away and gets a new class that I'll make
        });
      },
      child: new Text('Go to a new page but keep root, just replace this feed part'),
    );
  }
}`

And then import that file into your main file

`
 import 'package:flutter/material.dart';
 import 'feedPage.dart'
class RootPage extends StatefulWidget {
  @override
  _RootPageState createState() => new _RootPageState();
}
class _RootPageState extends State {
  FeedPage feedPage;

  Widget currentPage;

  @override
  void initState() {
    super.initState();
    feedPage = FeedPage();

    currentPage = feedPage;
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      //Current page to be changed from other classes too?
      body: currentPage
    );
  }
}`

In flutter you cant write multiple Stateful widgets in one dart file you have to create that as a widget and use it in your code as setState is an attribute of a Stateful widget we have write this code in an diffrent file

Problem Solved......:)