provider.dart

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

void main() {
  runApp(
    MultiProvider(
      providers: [
        ChangeNotifierProvider(create: (context) => VsjBank()),
      ],
      child: const VsjApp(),
    ),
  );
}

class VsjBank with ChangeNotifier {
  final Account _balance = Account();

  Account get balance => _balance;

  void deposit() {
    _balance.balance += 10;
    _balance.nooftransactions += 1;
    notifyListeners();
  }

  void withdraw() {
    _balance.balance -= 5;
    _balance.nooftransactions += 1;
    // notifyListeners();
  }

  void notify() {
    notifyListeners();
  }
}

class VsjApp extends StatelessWidget {
  const VsjApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Vsj Provider Demo'),
          centerTitle: true,
          backgroundColor: Colors.teal,
        ),
        body: Center(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              const Card(
                  child: Text(
                'Account Details',
                style: TextStyle(fontWeight: FontWeight.bold),
              )),
              const AccountManager(),
              Padding(
                padding: const EdgeInsets.all(8.0),
                child: ElevatedButton(
                  onPressed: () => context.read<VsjBank>().deposit(),
                  child: const Text('\nDeposit\nCalls notify\n'),
                ),
              ),
              Padding(
                padding: const EdgeInsets.all(8.0),
                child: ElevatedButton(
                  onPressed: () => context.read<VsjBank>().withdraw(),
                  child: const Text('\nWithdraw\nNo notify\n'),
                ),
              ),
              Padding(
                padding: const EdgeInsets.all(8.0),
                child: ElevatedButton(
                  onPressed: () => context.read<VsjBank>().notify(),
                  child: const Text('\nOnly Notify\n'),
                ),
              ),
              const Card(
                  child: Text(
                'Account Details Repeat',
                style: TextStyle(fontWeight: FontWeight.bold),
              )),
              const AccountManager(),
            ],
          ),
        ),
      ),
    );
  }
}

class AccountManager extends StatelessWidget {
  const AccountManager({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Text('Balance ${context.watch<VsjBank>().balance.balance}'),
        Text(
            'Transactions ${context.watch<VsjBank>().balance.nooftransactions}'),
      ],
    );
  }
}

class Account {
  int nooftransactions = 0, balance = 0;
  @override
  String toString() {
    return balance.toString();
  }
}