Flutter Set State onPressed on RaisedButton

you can implement using setState method.

i implement something like that just go through that.

import 'package:flutter/material.dart';  void main() {    runApp(MaterialApp(      title: 'Demo',      initialRoute: '/',      routes: {        '/': (context) => FirstScreen(),        '/second': (context) => SecondScreen(),      },    ));  }  class FirstScreen extends StatefulWidget {    @override    _FirstScreenState createState() => _FirstScreenState();  }  class _FirstScreenState extends State<FirstScreen> {    int submit = 0;    @override    Widget build(BuildContext context) {      return Scaffold(          appBar: AppBar(            title: Text("Demo"),          ),          body: new Column(            mainAxisSize: MainAxisSize.max,            mainAxisAlignment: MainAxisAlignment.center,            crossAxisAlignment: CrossAxisAlignment.center,            children: <Widget>[              Row(                children: <Widget>[                  new RaisedButton(                      padding: const EdgeInsets.all(10.0),                      child: const Text('Next Question'),                      color: submit == 0 ? Color(0xFFE9E9E9) : Colors.grey,                      elevation: 0.0,                      onPressed: () {                        submit == 0 ? null : Navigator.push(                          context,                          MaterialPageRoute(builder: (context) => SecondScreen()),                        );                      }                  ),                  new RaisedButton(                    padding: const EdgeInsets.all(10.0),                    child: const Text('Submit Answer'),                    color: Color(0xFFE08284),                    elevation: 0.0,                    onPressed: () {                      setState(() {                        submit = 1;                      });                    },                  ),                ],              ),              submit == 1 ? new Container(                child: new Text("hello World"),              ) : new Container()            ],          )      );    }  }  class SecondScreen extends StatelessWidget {    @override    Widget build(BuildContext context) {      return Scaffold(        appBar: AppBar(          title: Text("Second Screen"),        ),        body: Center(          child: RaisedButton(            onPressed: () {              Navigator.pop(context);            },            child: Text('Go back!'),          ),        ),      );    }  }