Counter example with file storage

home.dart

import 'dart:io';

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

class Home extends StatefulWidget {
  const Home({super.key});

  @override
  State<Home> createState() => _HomeState();
}

class _HomeState extends State<Home> {
  int counter = 0;

  @override
  void initState() {
    _initializeCounter();
    super.initState();
  }

  /// Loads and initializes [counter] from a file called counter.txt
  _initializeCounter() async {
    final Directory directory = await getApplicationDocumentsDirectory();
    String path = directory.path;
    File file = File('$path/counter.txt');
    if (await file.exists()) {
      String contents = await file.readAsString();
      counter = int.parse(contents);
      setState(() {});
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Ejemplo de Storage'),
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
      ),
      body: Center(
        child: Text(
          '$counter',
          style: Theme.of(context).textTheme.displayLarge,
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () async {
          counter++;
          setState(() {});

          /// Stores current [counter] value in a file called counter.txt
          final Directory directory = await getApplicationDocumentsDirectory();
          String path = directory.path;
          File file = File('$path/counter.txt');
          file.writeAsString('$counter');
        },
        child: const Icon(Icons.circle_rounded),
      ),
    );
  }
}