globalkey.dart

import 'package:flutter/material.dart';

GlobalKey<_CounterWidgetState> counterKey = GlobalKey<_CounterWidgetState>();

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

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        floatingActionButton: FloatingActionButton(
          onPressed: () {
            counterKey.currentState?.increment();
          },
          child: Icon(Icons.add),
        ),
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              CounterWidget(key: counterKey),
              ElevatedButton(
                onPressed: () {
                  counterKey.currentState?.reset();
                },
                child: Text('Reset Counter'),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

class CounterWidget extends StatefulWidget {
  CounterWidget({Key? key}) : super(key: key);

  @override
  _CounterWidgetState createState() => _CounterWidgetState();
}

class _CounterWidgetState extends State<CounterWidget> {
  int _count = 0;

  void increment() {
    setState(() {
      _count++;
    });
  }

  void reset() {
    setState(() {
      _count = 0;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Text('Count: $_count');
  }
}