import "package:flutter/material.dart";

final list = <int>[];

// Doesn't work.
//final test = () {
//  list.add(1);
//  print("[test] list: $list");  // does nothing, no output
//  print("[test] list: " + list.elementAt(0).toString());  // does nothing, no output
//}();

// Doesn't work.
//class Test {
//  Test() {
//    list.add(1);
//    print("[test] list: $list");  // does nothing, no output
//    print("[test] list: " + list.elementAt(0).toString());  // does nothing, no output
//  }
//}
//final test = Test();

class App extends StatefulWidget {
  @override
  _AppState createState() => _AppState();
}

class _AppState extends State<App> {
  @override
  void initState() {
    super.initState();

    print("[initState] list: $list");  // empty list (any test implementation)
    //print("[initState] list: " + list.elementAt(0).toString());  // throws (any test implementation)

    list.add(1);
    print("[initState][+] list: $list");  // ok
    print("[initState][+] list: " + list.elementAt(0).toString());  // ok
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(title: "Test", home: const Scaffold(body: Center(child: CircularProgressIndicator())));
  }
}

void main() {
  runApp(App());
}