Migrate to sound null safety

mvolpato · Mar 13, 2021 · ae460c3 · ae460c3
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.0.3] - migrate to sound null safety
+### Changed
+- code is now sound null safe
+
 ## [0.0.2] - add playlist
 ### Added
 - this changelog

diff --git a/README.md b/README.md
@@ -19,4 +19,10 @@ the package [just_audio](https://pub.dev/packages/just_audio).
 In the [second part](https://ishouldgotosleep.com/tutorials/music-app/repository-management-and-add-playlist/)
 we improve the repository and we add a playlist to the app.
 
-<img alt="The UI at the end of the first part" src="https://ishouldgotosleep.com/assets/images/blog/music-app/playlist.png" width="200" height="433">
+<img alt="The UI at the end of the first part" src="https://ishouldgotosleep.com/assets/images/blog/music-app/playlist.png" width="200" height="433">
+
+### Part 3: Migrate to Flutter 2, sound null safety, and select a license
+
+The [third part](https://ishouldgotosleep.com/tutorials/music-app/update-flutter-2-null-safety-add-license/)
+is all about upgrading Flutter and migrate to sound null safety. We also select a 
+license for the project.
diff --git a/ios/Podfile.lock b/ios/Podfile.lock
@@ -25,7 +25,7 @@ EXTERNAL SOURCES:
 
 SPEC CHECKSUMS:
   audio_session: 4f3e461722055d21515cf3261b64c973c062f345
-  Flutter: 0e3d915762c693b495b44d77113d4970485de6ec
+  Flutter: 434fef37c0980e73bb6479ef766c45957d4b510c
   just_audio: baa7252489dbcf47a4c7cc9ca663e9661c99aafa
   path_provider: abfe2b5c733d04e238b0d8691db0cfd63a27a93c
 

diff --git a/ios/Runner.xcodeproj/project.xcworkspace/contents.xcworkspacedata b/ios/Runner.xcodeproj/project.xcworkspace/contents.xcworkspacedata
diff --git a/lib/domain/audio_metadata.dart b/lib/domain/audio_metadata.dart
@@ -15,5 +15,7 @@ class AudioMetadata {
   /// URL to an image representing this audio source.
   final String artwork;
 
-  AudioMetadata({this.title, this.artwork});
+  // TODO change placeholder
+  AudioMetadata(
+      {required this.title, this.artwork = 'https://via.placeholder.com/150'});
 }
diff --git a/lib/screens/commons/player_buttons.dart b/lib/screens/commons/player_buttons.dart
@@ -14,7 +14,7 @@ import 'package:just_audio/just_audio.dart';
 ///
 /// The order is: shuffle, previous, play/pause/restart, next, repeat.
 class PlayerButtons extends StatelessWidget {
-  const PlayerButtons(this._audioPlayer, {Key key}) : super(key: key);
+  const PlayerButtons(this._audioPlayer, {Key? key}) : super(key: key);
 
   final AudioPlayer _audioPlayer;
 
@@ -31,7 +31,7 @@ class PlayerButtons extends StatelessWidget {
           },
         ),
         // Previous
-        StreamBuilder<SequenceState>(
+        StreamBuilder<SequenceState?>(
           stream: _audioPlayer.sequenceStateStream,
           builder: (_, __) {
             return _previousButton();
@@ -46,7 +46,7 @@ class PlayerButtons extends StatelessWidget {
           },
         ),
         // Next
-        StreamBuilder<SequenceState>(
+        StreamBuilder<SequenceState?>(
           stream: _audioPlayer.sequenceStateStream,
           builder: (_, __) {
             return _nextButton();
@@ -69,7 +69,7 @@ class PlayerButtons extends StatelessWidget {
   /// If the audio has finished playing, a restart button is shown.
   /// If the audio is paused, or not started yet, a play button is shown.
   /// If the audio is loading, a progress indicator is shown.
-  Widget _playPauseButton(PlayerState playerState) {
+  Widget _playPauseButton(PlayerState? playerState) {
     final processingState = playerState?.processingState;
     if (processingState == ProcessingState.loading ||
         processingState == ProcessingState.buffering) {
@@ -96,7 +96,7 @@ class PlayerButtons extends StatelessWidget {
         icon: Icon(Icons.replay),
         iconSize: 64.0,
         onPressed: () => _audioPlayer.seek(Duration.zero,
-            index: _audioPlayer.effectiveIndices.first),
+            index: _audioPlayer.effectiveIndices?.first),
       );
     }
   }

diff --git a/lib/screens/commons/playlist.dart b/lib/screens/commons/playlist.dart
@@ -15,16 +15,17 @@ import 'package:just_audio/just_audio.dart';
 /// Audio sources are displayed with a `ListTile` with a leading image (the
 /// artwork), and the title of the audio source.
 class Playlist extends StatelessWidget {
-  const Playlist(this._audioPlayer, {Key key}) : super(key: key);
+  const Playlist(this._audioPlayer, {Key? key}) : super(key: key);
 
   final AudioPlayer _audioPlayer;
 
   Widget build(BuildContext context) {
-    return StreamBuilder<SequenceState>(
+    return StreamBuilder<SequenceState?>(
       stream: _audioPlayer.sequenceStateStream,
       builder: (context, snapshot) {
         final state = snapshot.data;
-        final sequence = state?.sequence ?? [];
+        if (state == null) return CircularProgressIndicator();
+        final sequence = state.sequence;
         return ListView(
           children: [
             for (var i = 0; i < sequence.length; i++)

diff --git a/lib/screens/player.dart b/lib/screens/player.dart
@@ -23,7 +23,7 @@ class Player extends StatefulWidget {
 }
 
 class _PlayerState extends State<Player> {
-  AudioPlayer _audioPlayer;
+  late AudioPlayer _audioPlayer;
 
   @override
   void initState() {