2 state 2 button (change value and rebuild widget)

 import 'package:flutter/material.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:  const MyHomePage(),

    );

  }

}

class MyHomePage extends StatefulWidget {

  const MyHomePage({Key? key}) : super(key: key);

  @override

  State<MyHomePage> createState() => _MyHomePageState();

}

class _MyHomePageState extends State<MyHomePage> {

  int _counterA = 0;

  int _counterB = 0;

  void _incrementCounterA() {

    setState(() {

      _counterA++;

    });

  }

  void _incrementCounterB() {

    setState(() {

      _counterB++;

    });

  }

  @override

  Widget build(BuildContext context) {

    return Scaffold(

      appBar: AppBar(

        title: const Text("App title"),

      ),

      body: Center(

        child: Column(

          mainAxisAlignment: MainAxisAlignment.center,

          children: <Widget>[

            Text(

              'A:'+'$_counterA',

              style: Theme.of(context).textTheme.headline4,

            ),

            TextButton(

              onPressed: _incrementCounterA,

              child: const Text('A'),

            ),

            Text(

              'B:'+'$_counterB',

              style: Theme.of(context).textTheme.headline4,

            ),

            TextButton(

              onPressed: _incrementCounterB,

              child: const Text('B'),

            ),

          ],

        ),

      ),

    );

  }

}