When I close my app, my database is resetting

Question

I am using the hive database to store the money variable. I want to access this database from different pages, so I defined the box on the globals.dart page. I just want this box to be null when the application is first opened, but every time I open the application globals.box returns null and my money variable is resetting to 1000. How can I fix this?

This is my main file:

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  globals.isLoggedIn = true;
  
  await Hive.initFlutter();
  await Hive.openBox<int>('stat');
  
  if (globals.box == null) {
    globals.box = Hive.box<int>('stat');
    globals.box.put('money', 1000);
  }
  runApp(MyApp());
}

This is my globals file

library my_prj.globals;
import 'package:hive/hive.dart';

bool isLoggedIn = false;
Box<int> box;

I am using this code to change the money variable:

import 'package:app1/globals.dart' as globals;    
globals.box.put('money', globals.box.get('money') + 100);

Answer 1

You can copy paste run two full code below
Step 1: You can use globals.box = await Hive.openBox<int>('stat');
Step 2: Check globals.box.get('money') == null, and set default value to 1000

code snippet

  globals.box = await Hive.openBox<int>('stat');

  if (globals.box.get('money') == null) {
    print("box is null, set defaul value to 1000");
    globals.box.put('money', 1000);
  } else {
    print("box is not null, current value is ${globals.box.get('money')}");
  }

output for first time open App

I/flutter ( 8143): box is null, set defaul value to 1000

click button and second time open App

I/flutter ( 8217): box is not null, current value is 1100

full code main.dart

import 'package:flutter/material.dart';
import 'package:hive/hive.dart';
import 'package:hive_flutter/hive_flutter.dart';
import 'globals.dart' as globals;

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  globals.isLoggedIn = true;

  await Hive.initFlutter();
  globals.box = await Hive.openBox<int>('stat');

  if (globals.box.get('money') == null) {
    print("box is null, set defaul value to 1000");
    globals.box.put('money', 1000);
  } else {
    print("box is not null, current value is ${globals.box.get('money')}");
  }
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            RaisedButton(
              onPressed: () {
                globals.box.put('money', globals.box.get('money') + 100);
              },
              child: Text("click"),
            ),
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}

full code globals.dart

library my_prj.globals;
import 'package:hive/hive.dart';

bool isLoggedIn = false;
Box<int> box;