我希望Flutter应用程序在每次向SQLite数据库添加新数据时自动刷新变量

import 'package:flutter/material.dart';
import 'package:sqflite/sqflite.dart';
import 'package:path/path.dart';

class DatabaseHelper {
  static final DatabaseHelper _instance = DatabaseHelper.internal();
  factory DatabaseHelper() => _instance;

  static Database? _db;

  Future<Database?> get db async {
    if (_db != null) {
      return _db;
    }
    _db = await initDb();
    return _db;
  }

  DatabaseHelper.internal();

  Future<Database> initDb() async {
    String databasesPath = await getDatabasesPath();
    String path = join(databasesPath, 'my_database.db');
    return await openDatabase(path, version: 1, onCreate: _onCreate);
  }

  void _onCreate(Database db, int version) async {
    await db.execute('CREATE TABLE IF NOT EXISTS my_table (id INTEGER PRIMARY KEY, data TEXT)');
  }

  Future<int> insertData(String data) async {
    Database? database = await db;
    return await database!.insert('my_table', {'data': data});
  }

  Future<List<Map<String, dynamic>>> getData() async {
    Database? database = await db;
    return await database!.query('my_table');
  }
}

class MyApp extends StatelessWidget {
  final dbHelper = DatabaseHelper();

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Flutter App'),
        ),
        body: Center(
          child: ElevatedButton(
            child: Text('Add Data'),
            onPressed: () async {
              await dbHelper.insertData('New Data');
              setState(() {}); // 刷新界面
            },
          ),
        ),
      ),
    );
  }
}