lib file

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

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

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      home: HomePage('flutter demo', Colors.brown, true),
    );
  }
}
import 'package:flutter/material.dart';
import 'package:myapp/center_widget.dart';
import 'package:myapp/second_screen.dart';

class HomePage extends StatefulWidget {
  const HomePage(this.title, this.color, this.center, {super.key});

  final String title;
  final Color color;
  final bool center;

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {

 var activeScreen = 'centerWidget';

  void switchScreen() {
    setState(() {
      activeScreen = 'secondScreen';
    });
  } 
import 'package:flutter/material.dart';

class CenterWidget extends StatelessWidget {
  const CenterWidget(this.press,this.text, {super.key});
  final void Function() press;
  final String text;

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: <Widget>[
          container,
          SizedBox(height: 39),
          OutlinedButton.icon(
            style: OutlinedButton.styleFrom(
            ),
            onPressed: press,
            icon: Icon(Icons.person_search),
            label: Text(text),
          ),
        ],
      ),
    );
  }
}

Container container = Container(width: 110, height: 150, color: Colors.brown);
import 'package:flutter/material.dart';

class SecondScreen extends StatelessWidget {
 const  SecondScreen(this.text1, {super.key});

  final String text1;

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      width: double.infinity,
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
        Container(
          width:150,
          height: 200,
          color: Colors.brown,
        ),
        Text(text1),
       ],
      ),
    );
  }
}