Migrate 101-starter to NNBD (#222)

* Update version.

* Migrate.

mdc_100_series/lib/app.dart

@@ -35,7 +35,7 @@ class ShrineApp extends StatelessWidget {
     );
   }
 
-  Route<dynamic> _getRoute(RouteSettings settings) {
+  Route<dynamic>? _getRoute(RouteSettings settings) {
     if (settings.name != '/login') {
       return null;
     }

mdc_100_series/lib/model/product.dart

@@ -12,22 +12,16 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-import 'package:flutter/foundation.dart';
-
 enum Category { all, accessories, clothing, home, }
 
 class Product {
   const Product({
-    @required this.category,
-    @required this.id,
-    @required this.isFeatured,
-    @required this.name,
-    @required this.price,
-  })  : assert(category != null),
-        assert(id != null),
-        assert(isFeatured != null),
-        assert(name != null),
-        assert(price != null);
+    required this.category,
+    required this.id,
+    required this.isFeatured,
+    required this.name,
+    required this.price,
+  });
 
   final Category category;
   final int id;

mdc_100_series/lib/supplemental/asymmetric_view.dart

@@ -20,10 +20,10 @@ import 'product_columns.dart';
 class AsymmetricView extends StatelessWidget {
   final List<Product> products;
 
-  AsymmetricView({Key key, this.products});
+  AsymmetricView({Key? key, required this.products});
 
   List<Container> _buildColumns(BuildContext context) {
-    if (products == null || products.isEmpty) {
+    if (products.isEmpty) {
       return <Container>[];
     }
 

mdc_100_series/lib/supplemental/cut_corners_border.dart

@@ -19,21 +19,21 @@ import 'package:flutter/widgets.dart';
 
 class CutCornersBorder extends OutlineInputBorder {
   const CutCornersBorder({
-    BorderSide borderSide: const BorderSide(),
-    BorderRadius borderRadius: const BorderRadius.all(Radius.circular(2.0)),
-    this.cut: 7.0,
-    double gapPadding: 2.0,
+    BorderSide borderSide = const BorderSide(),
+    BorderRadius borderRadius = const BorderRadius.all(Radius.circular(2.0)),
+    this.cut = 7.0,
+    double gapPadding = 2.0,
   }) : super(
             borderSide: borderSide,
             borderRadius: borderRadius,
             gapPadding: gapPadding);
 
   @override
   CutCornersBorder copyWith({
-    BorderSide borderSide,
-    BorderRadius borderRadius,
-    double gapPadding,
-    double cut,
+    BorderSide? borderSide,
+    BorderRadius? borderRadius,
+    double? gapPadding,
+    double? cut,
   }) {
     return CutCornersBorder(
       borderRadius: borderRadius ?? this.borderRadius,
@@ -46,11 +46,11 @@ class CutCornersBorder extends OutlineInputBorder {
   final double cut;
 
   @override
-  ShapeBorder lerpFrom(ShapeBorder a, double t) {
+  ShapeBorder? lerpFrom(ShapeBorder? a, double t) {
     if (a is CutCornersBorder) {
       final CutCornersBorder outline = a;
       return CutCornersBorder(
-        borderRadius: BorderRadius.lerp(outline.borderRadius, borderRadius, t),
+        borderRadius: BorderRadius.lerp(outline.borderRadius, borderRadius, t)!,
         borderSide: BorderSide.lerp(outline.borderSide, borderSide, t),
         cut: cut,
         gapPadding: outline.gapPadding,
@@ -60,11 +60,11 @@ class CutCornersBorder extends OutlineInputBorder {
   }
 
   @override
-  ShapeBorder lerpTo(ShapeBorder b, double t) {
+  ShapeBorder? lerpTo(ShapeBorder? b, double t) {
     if (b is CutCornersBorder) {
       final CutCornersBorder outline = b;
       return CutCornersBorder(
-        borderRadius: BorderRadius.lerp(borderRadius, outline.borderRadius, t),
+        borderRadius: BorderRadius.lerp(borderRadius, outline.borderRadius, t)!,
         borderSide: BorderSide.lerp(borderSide, outline.borderSide, t),
         cut: cut,
         gapPadding: outline.gapPadding,
@@ -103,12 +103,11 @@ class CutCornersBorder extends OutlineInputBorder {
   void paint(
     Canvas canvas,
     Rect rect, {
-    double gapStart,
+    double? gapStart,
     double gapExtent: 0.0,
     double gapPercentage: 0.0,
-    TextDirection textDirection,
+    TextDirection? textDirection,
   }) {
-    assert(gapExtent != null);
     assert(gapPercentage >= 0.0 && gapPercentage <= 1.0);
 
     final Paint paint = borderSide.toPaint();
@@ -117,8 +116,8 @@ class CutCornersBorder extends OutlineInputBorder {
       canvas.drawPath(_notchedCornerPath(outer.middleRect), paint);
     } else {
       final double extent =
-          lerpDouble(0.0, gapExtent + gapPadding * 2.0, gapPercentage);
-      switch (textDirection) {
+          lerpDouble(0.0, gapExtent + gapPadding * 2.0, gapPercentage)!;
+      switch (textDirection!) {
         case TextDirection.rtl:
           {
             final Path path = _notchedCornerPath(

mdc_100_series/lib/supplemental/product_card.dart

@@ -18,8 +18,8 @@ import 'package:intl/intl.dart';
 import '../model/product.dart';
 
 class ProductCard extends StatelessWidget {
-  ProductCard({this.imageAspectRatio: 33 / 49, this.product})
-      : assert(imageAspectRatio == null || imageAspectRatio > 0);
+  ProductCard({this.imageAspectRatio = 33 / 49, required this.product})
+      : assert(imageAspectRatio > 0);
 
   final double imageAspectRatio;
   final Product product;
@@ -54,15 +54,15 @@ class ProductCard extends StatelessWidget {
             crossAxisAlignment: CrossAxisAlignment.center,
             children: <Widget>[
               Text(
-                product == null ? '' : product.name,
+                product.name,
                 style: theme.textTheme.headline6,
                 softWrap: false,
                 overflow: TextOverflow.ellipsis,
                 maxLines: 1,
               ),
               SizedBox(height: 4.0),
               Text(
-                product == null ? '' : formatter.format(product.price),
+                formatter.format(product.price),
                 style: theme.textTheme.subtitle2,
               ),
             ],

mdc_100_series/lib/supplemental/product_columns.dart

@@ -19,11 +19,12 @@ import 'product_card.dart';
 
 class TwoProductCardColumn extends StatelessWidget {
   TwoProductCardColumn({
-    this.bottom,
+    required this.bottom,
     this.top,
-  }) : assert(bottom != null);
+  });
 
-  final Product bottom, top;
+  final Product bottom;
+  final Product? top;
 
   @override
   Widget build(BuildContext context) {
@@ -46,7 +47,7 @@ class TwoProductCardColumn extends StatelessWidget {
             child: top != null
                 ? ProductCard(
                     imageAspectRatio: imageAspectRatio,
-                    product: top,
+                    product: top!,
                   )
                 : SizedBox(
                     height: heightOfCards,
@@ -67,7 +68,7 @@ class TwoProductCardColumn extends StatelessWidget {
 }
 
 class OneProductCardColumn extends StatelessWidget {
-  OneProductCardColumn({this.product});
+  OneProductCardColumn({required this.product});
 
   final Product product;
 

mdc_100_series/pubspec.yaml

@@ -1,10 +1,13 @@
 name: Shrine
 description: Learn the basics of using Material Components by building a simple app with core components.
 
+environment:
+  sdk: '>=2.12.0-0 <3.0.0'
+
 dependencies:
   flutter:
     sdk: flutter
-  intl: ^0.15.6
+  intl: ^0.17.0-nullsafety.2
 
   cupertino_icons: ^0.1.0
   shrine_images: 1.1.1