Null safety in Flutter
Null safety is available in the Flutter beta channel,
starting with build 1.24.0-10.2.pre
.
You can now migrate your Flutter packages to use non-nullable types like this:
class MyApp extends StatelessWidget { final int anInt = 3; // Cannot be null. final int? aNullableInt = null; // Can be null. @override Widget build(BuildContext context) { return MaterialApp( title: 'Nullable Fields Demo', home: Scaffold( appBar: AppBar( title: Text('Nullable Fields Demo'), ), body: Center( child: Column( children: [ Text('anInt is $anInt.'), Text('aNullableInt is $aNullableInt.'), ], ), ), ), ); } }
To learn about null safety, read these pages:
- Sound null safety: The null safety homepage. Has basic information, with links to everything else you might need.
- Understanding null safety: A deep dive into null safety, written by Dart engineer Bob Nystrom.
When you’re ready to start migrating your packages to null safety, check out these pages:
- Migrating to null safety: Instructions for converting your packages to null safety.
- Unsound null safety: Conceptual and practical information about mixed-mode programs, in which only some libraries are null safe.
- FAQ: Questions that have come up during migration to null safety.