Upgrading samples to flutter_lints, part 1 of n (#804)

platform_channels/lib/main.dart

@@ -68,7 +68,7 @@ class HomePage extends StatelessWidget {
   Widget build(BuildContext context) {
     return Scaffold(
       appBar: AppBar(
-        title: Text('Platform Channel Sample'),
+        title: const Text('Platform Channel Sample'),
       ),
       body: ListView(
         children: demoList.map((demoInfo) => DemoTile(demoInfo)).toList(),
@@ -81,7 +81,7 @@ class HomePage extends StatelessWidget {
 class DemoTile extends StatelessWidget {
   final DemoInfo demoInfo;
 
-  DemoTile(this.demoInfo);
+  const DemoTile(this.demoInfo);
 
   @override
   Widget build(BuildContext context) {

platform_channels/lib/src/accelerometer_event_channel.dart

@@ -8,7 +8,7 @@ import 'package:flutter/services.dart';
 /// changes from the Accelerometer sensor from native side. It has a [readings]
 /// getter to provide a stream of [AccelerometerReadings].
 class Accelerometer {
-  static final _eventChannel = const EventChannel('eventChannelDemo');
+  static const _eventChannel = EventChannel('eventChannelDemo');
 
   /// Method responsible for providing a stream of [AccelerometerReadings] to listen
   /// to value changes from the Accelerometer sensor.

platform_channels/lib/src/add_pet_details.dart

@@ -22,10 +22,10 @@ class _AddPetDetailsState extends State<AddPetDetails> {
   Widget build(BuildContext context) {
     return Scaffold(
       appBar: AppBar(
-        title: Text('Add Pet Details'),
+        title: const Text('Add Pet Details'),
         actions: <Widget>[
           IconButton(
-            icon: Icon(Icons.add),
+            icon: const Icon(Icons.add),
             onPressed: () {
               PetListMessageChannel.addPetDetails(
                 PetDetails(
@@ -43,19 +43,19 @@ class _AddPetDetailsState extends State<AddPetDetails> {
         padding: const EdgeInsets.all(8.0),
         child: Column(
           children: [
-            SizedBox(
+            const SizedBox(
               height: 8,
             ),
             TextField(
               controller: breedTextController,
-              decoration: InputDecoration(
+              decoration: const InputDecoration(
                 border: OutlineInputBorder(),
                 filled: true,
                 hintText: 'Breed of pet',
                 labelText: 'Breed',
               ),
             ),
-            SizedBox(
+            const SizedBox(
               height: 8,
             ),
             RadioListTile<String>(

platform_channels/lib/src/event_channel_demo.dart

@@ -19,7 +19,7 @@ class EventChannelDemo extends StatelessWidget {
     final textStyle = Theme.of(context).textTheme.headline5;
     return Scaffold(
       appBar: AppBar(
-        title: Text('EventChannel Demo'),
+        title: const Text('EventChannel Demo'),
       ),
       body: Center(
         child: StreamBuilder<AccelerometerReadings>(

platform_channels/lib/src/image_basic_message_channel.dart

@@ -10,8 +10,8 @@ import 'package:flutter/services.dart';
 /// from a native asset. The [BasicMessageChannel] uses [StandardMessageCodec]
 /// since it supports [Uint8List], which is used to transport the image data.
 class PlatformImageFetcher {
-  static final _basicMessageChannel = const BasicMessageChannel<dynamic>(
-      'platformImageDemo', StandardMessageCodec());
+  static const _basicMessageChannel =
+      BasicMessageChannel<dynamic>('platformImageDemo', StandardMessageCodec());
 
   /// Method responsible for providing the platform image.
   static Future<Uint8List> getImage() async {

platform_channels/lib/src/method_channel_demo.dart

@@ -29,7 +29,7 @@ class _MethodChannelDemoState extends State<MethodChannelDemo> {
             'Value of count is $count',
             style: Theme.of(context).textTheme.headline5,
           ),
-          SizedBox(
+          const SizedBox(
             height: 16,
           ),
           Row(
@@ -49,8 +49,8 @@ class _MethodChannelDemoState extends State<MethodChannelDemo> {
                     );
                   }
                 },
-                icon: Icon(Icons.add),
-                label: Text('Increment'),
+                icon: const Icon(Icons.add),
+                label: const Text('Increment'),
               ),
 
               // Whenever users press the ElevatedButton, it invokes
@@ -67,8 +67,8 @@ class _MethodChannelDemoState extends State<MethodChannelDemo> {
                     );
                   }
                 },
-                icon: Icon(Icons.remove),
-                label: Text('Decrement'),
+                icon: const Icon(Icons.remove),
+                label: const Text('Decrement'),
               )
             ],
           )

platform_channels/lib/src/pet_list_message_channel.dart

@@ -9,10 +9,10 @@ import 'package:flutter/services.dart';
 /// This class includes two methods [addPetDetails] and [removePet] which are used
 /// to add a new pet and remove a pet from the the list respectively.
 class PetListMessageChannel {
-  static final _jsonMessageCodecChannel =
+  static const _jsonMessageCodecChannel =
       BasicMessageChannel<dynamic>('jsonMessageCodecDemo', JSONMessageCodec());
 
-  static final _binaryCodecChannel =
+  static const _binaryCodecChannel =
       BasicMessageChannel('binaryCodecDemo', BinaryCodec());
 
   /// Method to add a new pet to the list.

platform_channels/lib/src/pet_list_screen.dart

@@ -22,7 +22,7 @@ class _PetListScreenState extends State<PetListScreen> {
     super.initState();
     // Receives a string of json object from the platform and converts it
     // to PetModel.
-    BasicMessageChannel('stringCodecDemo', StringCodec())
+    const BasicMessageChannel('stringCodecDemo', StringCodec())
         .setMessageHandler((message) async {
       if (message == null) {
         showSnackBar('An error occurred while adding pet details.', context);
@@ -40,16 +40,16 @@ class _PetListScreenState extends State<PetListScreen> {
     return Scaffold(
       key: scaffoldKey,
       appBar: AppBar(
-        title: Text('Pet List'),
+        title: const Text('Pet List'),
       ),
       floatingActionButton: FloatingActionButton(
-        child: Icon(Icons.add),
+        child: const Icon(Icons.add),
         onPressed: () {
           Navigator.pushNamed(context, '/addPetDetails');
         },
       ),
       body: petListModel?.petList?.isEmpty ?? true
-          ? Center(child: Text('Enter Pet Details'))
+          ? const Center(child: Text('Enter Pet Details'))
           : BuildPetList(petListModel.petList),
     );
   }
@@ -59,12 +59,12 @@ class _PetListScreenState extends State<PetListScreen> {
 class BuildPetList extends StatelessWidget {
   final List<PetDetails> petList;
 
-  BuildPetList(this.petList);
+  const BuildPetList(this.petList);
 
   @override
   Widget build(BuildContext context) {
     return ListView.builder(
-      padding: EdgeInsets.all(8),
+      padding: const EdgeInsets.all(8),
       itemCount: petList.length,
       itemBuilder: (context, index) {
         return ListTile(
@@ -73,7 +73,7 @@ class BuildPetList extends StatelessWidget {
             'Pet type: ${petList[index].petType}',
           ),
           trailing: IconButton(
-            icon: Icon(Icons.delete),
+            icon: const Icon(Icons.delete),
             onPressed: () async {
               try {
                 await PetListMessageChannel.removePet(index);

platform_channels/lib/src/platform_image_demo.dart

@@ -24,7 +24,7 @@ class _PlatformImageDemoState extends State<PlatformImageDemo> {
   Widget build(BuildContext context) {
     return Scaffold(
       appBar: AppBar(
-        title: Text('Platform Image Demo'),
+        title: const Text('Platform Image Demo'),
       ),
       body: Center(
         child: Column(
@@ -38,7 +38,7 @@ class _PlatformImageDemoState extends State<PlatformImageDemo> {
                   future: imageData,
                   builder: (context, snapshot) {
                     if (snapshot.connectionState == ConnectionState.none) {
-                      return Placeholder();
+                      return const Placeholder();
                     } else if (snapshot.hasError) {
                       return Center(
                         child: Text(snapshot.error.toString()),
@@ -50,12 +50,12 @@ class _PlatformImageDemoState extends State<PlatformImageDemo> {
                         fit: BoxFit.fill,
                       );
                     }
-                    return CircularProgressIndicator();
+                    return const CircularProgressIndicator();
                   },
                 ),
               ),
             ),
-            SizedBox(
+            const SizedBox(
               height: 16,
             ),
             ElevatedButton(
@@ -66,7 +66,7 @@ class _PlatformImageDemoState extends State<PlatformImageDemo> {
                         imageData = PlatformImageFetcher.getImage();
                       });
                     },
-              child: Text('Get Image'),
+              child: const Text('Get Image'),
             )
           ],
         ),