Fixed dart analytic issues

example/android/app/src/main/AndroidManifest.xml

@@ -13,8 +13,7 @@
          additional functionality it is fine to subclass or reimplement
          FlutterApplication and put your custom class here. -->
     <application
-        android:name="io.flutter.app.FlutterApplication"
-        android:label="language_pickers_demo"
+        android:label="language_pickers_demo" android:theme="@style/LaunchTheme"
         android:icon="@mipmap/ic_launcher">
         <activity
             android:name=".MainActivity"
@@ -23,10 +22,15 @@
             android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|layoutDirection|fontScale|screenLayout|density"
             android:hardwareAccelerated="true"
             android:windowSoftInputMode="adjustResize">
+            <meta-data
+                android:name="flutterEmbedding"
+                android:value="2" />
+
             <!-- This keeps the window background of the activity showing
                  until Flutter renders its first frame. It can be removed if
                  there is no splash screen (such as the default splash screen
                  defined in @style/LaunchTheme). -->
+
             <meta-data
                 android:name="io.flutter.app.android.SplashScreenUntilFirstFrame"
                 android:value="true" />

example/android/app/src/main/java/net/demo/languagepickersdemo/MainActivity.java

@@ -7,7 +7,5 @@
 public class MainActivity extends FlutterActivity {
   @Override
   protected void onCreate(Bundle savedInstanceState) {
-    super.onCreate(savedInstanceState);
-    GeneratedPluginRegistrant.registerWith(this);
   }
 }

lib/language_picker_cupertino.dart

@@ -9,11 +9,11 @@ const double defaultPickerItemHeight = 32.0;
 /// in cupertino style
 class LanguagePickerCupertino extends StatefulWidget {
   /// Callback that is called with selected Language
-  final ValueChanged<Language> onValuePicked;
+  final ValueChanged<Language>? onValuePicked;
 
   ///Callback that is called with selected item of type Language which returns a
   ///Widget to build list view item inside dialog
-  final ItemBuilder itemBuilder;
+  final ItemBuilder? itemBuilder;
 
   ///The [itemExtent] of [CupertinoPicker]
   /// The uniform height of all children.
@@ -26,7 +26,7 @@ class LanguagePickerCupertino extends StatefulWidget {
   final double pickerSheetHeight;
 
   ///The TextStyle that is applied to Text widgets inside item
-  final TextStyle textStyle;
+  final TextStyle? textStyle;
 
   /// Relative ratio between this picker's height and the simulated cylinder's diameter.
   ///
@@ -35,35 +35,35 @@ class LanguagePickerCupertino extends StatefulWidget {
   /// For more details, see [ListWheelScrollView.diameterRatio].
   ///
   /// Must not be null and defaults to `1.1` to visually mimic iOS.
-  final double diameterRatio;
+  final double? diameterRatio;
 
   /// Background color behind the children.
   ///
   /// Defaults to a gray color in the iOS color palette.
   ///
   /// This can be set to null to disable the background painting entirely; this
   /// is mildly more efficient than using [Colors.transparent].
-  final Color backgroundColor;
+  final Color? backgroundColor;
 
   /// {@macro flutter.rendering.wheelList.offAxisFraction}
-  final double offAxisFraction;
+  final double? offAxisFraction;
 
   /// {@macro flutter.rendering.wheelList.useMagnifier}
-  final bool useMagnifier;
+  final bool? useMagnifier;
 
   /// {@macro flutter.rendering.wheelList.magnification}
-  final double magnification;
+  final double? magnification;
 
   /// A [FixedExtentScrollController] to read and control the current item.
   ///
   /// If null, an implicit one will be created internally.
-  final FixedExtentScrollController scrollController;
+  final FixedExtentScrollController? scrollController;
 
   /// List of languages available in this picker.
-  final List<Map<String, String>> languagesList;
+  final List<Map<String, String>>? languagesList;
 
   const LanguagePickerCupertino({
-    Key key,
+    Key? key,
     this.onValuePicked,
     this.itemBuilder,
     this.pickerItemHeight = defaultPickerItemHeight,
@@ -83,7 +83,7 @@ class LanguagePickerCupertino extends StatefulWidget {
 }
 
 class _CupertinoLanguagePickerState extends State<LanguagePickerCupertino> {
-  List<Language> _allLanguages;
+  late List<Language> _allLanguages;
 
   @override
   void initState() {
@@ -124,11 +124,11 @@ class _CupertinoLanguagePickerState extends State<LanguagePickerCupertino> {
       backgroundColor: CupertinoColors.white,
       children: _allLanguages
           .map<Widget>((Language language) => widget.itemBuilder != null
-              ? widget.itemBuilder(language)
+              ? widget.itemBuilder!(language)
               : _buildDefaultItem(language))
           .toList(),
       onSelectedItemChanged: (int index) {
-        widget.onValuePicked(_allLanguages[index]);
+        widget.onValuePicked!(_allLanguages[index]);
       },
     );
   }

lib/language_picker_dialog.dart

@@ -11,13 +11,13 @@ import 'languages.dart';
 
 class LanguagePickerDialog extends StatefulWidget {
   /// Callback that is called with selected Language
-  final ValueChanged<Language> onValuePicked;
+  final ValueChanged<Language>? onValuePicked;
 
   /// The (optional) title of the dialog is displayed in a large font at the top
   /// of the dialog.
   ///
   /// Typically a [Text] widget.
-  final Widget title;
+  final Widget? title;
 
   /// Padding around the title.
   ///
@@ -29,7 +29,7 @@ class LanguagePickerDialog extends StatefulWidget {
   /// provided (but see [contentPadding]). If it _is_ null, then an extra 20
   /// pixels of bottom padding is added to separate the [title] from the
   /// [actions].
-  final EdgeInsetsGeometry titlePadding;
+  final EdgeInsetsGeometry? titlePadding;
 
   /// Padding around the content.
 
@@ -46,11 +46,11 @@ class LanguagePickerDialog extends StatefulWidget {
   ///
   ///  * [SemanticsConfiguration.isRouteName], for a description of how this
   ///    value is used.
-  final String semanticLabel;
+  final String? semanticLabel;
 
   ///Callback that is called with selected item of type Language which returns a
   ///Widget to build list view item inside dialog
-  final ItemBuilder itemBuilder;
+  final ItemBuilder? itemBuilder;
 
   /// The (optional) horizontal separator used between title, content and
   /// actions.
@@ -67,19 +67,19 @@ class LanguagePickerDialog extends StatefulWidget {
   final bool isSearchable;
 
   /// The optional [decoration] of search [TextField]
-  final InputDecoration searchInputDecoration;
+  final InputDecoration? searchInputDecoration;
 
   ///The optional [cursorColor] of search [TextField]
-  final Color searchCursorColor;
+  final Color? searchCursorColor;
 
   ///The search empty view is displayed if nothing returns from search result
-  final Widget searchEmptyView;
+  final Widget? searchEmptyView;
 
   /// List of languages available in this picker.
-  final List<Map<String, String>> languagesList;
+  final List<Map<String, String>>? languagesList;
 
   LanguagePickerDialog({
-    Key key,
+    Key? key,
     this.onValuePicked,
     this.title,
     this.titlePadding,
@@ -104,8 +104,8 @@ class LanguagePickerDialog extends StatefulWidget {
 }
 
 class SingleChoiceDialogState extends State<LanguagePickerDialog> {
-  List<Language> _allLanguages;
-  List<Language> _filteredLanguages;
+  late List<Language> _allLanguages;
+  late List<Language> _filteredLanguages;
 
   @override
   void initState() {
@@ -134,10 +134,10 @@ class SingleChoiceDialogState extends State<LanguagePickerDialog> {
             children: _filteredLanguages
                 .map((item) => SimpleDialogOption(
                       child: widget.itemBuilder != null
-                          ? widget.itemBuilder(item)
+                          ? widget.itemBuilder!(item)
                           : Text(item.name),
                       onPressed: () {
-                        widget.onValuePicked(item);
+                        widget.onValuePicked!(item);
                         Navigator.pop(context);
                       },
                     ))
@@ -163,7 +163,7 @@ class SingleChoiceDialogState extends State<LanguagePickerDialog> {
   _buildTitle() {
     return widget.titlePadding != null
         ? Padding(
-            padding: widget.titlePadding,
+            padding: widget.titlePadding!,
             child: widget.title,
           )
         : widget.title;

lib/language_picker_dropdown.dart

@@ -11,25 +11,25 @@ class LanguagePickerDropdown extends StatefulWidget {
   ///If it is not provided, default one will be used which displays
   ///flag image, isoCode and phoneCode in a row.
   ///Check _buildDefaultMenuItem method for details.
-  final ItemBuilder itemBuilder;
+  final ItemBuilder? itemBuilder;
 
   ///It should be one of the ISO ALPHA-2 Code that is provided
   ///in languagesList map of languages.dart file.
-  final String initialValue;
+  final String? initialValue;
 
   ///This function will be called whenever a Language item is selected.
-  final ValueChanged<Language> onValuePicked;
+  final ValueChanged<Language>? onValuePicked;
 
   /// List of languages available in this picker.
-  final List<Map<String, String>> languagesList;
+  final List<Map<String, String>>? languagesList;
 
   @override
   _LanguagePickerDropdownState createState() => _LanguagePickerDropdownState();
 }
 
 class _LanguagePickerDropdownState extends State<LanguagePickerDropdown> {
-  List<Language> _languages;
-  Language _selectedLanguage;
+  late List<Language> _languages;
+  late Language _selectedLanguage;
 
   @override
   void initState() {
@@ -58,7 +58,7 @@ class _LanguagePickerDropdownState extends State<LanguagePickerDropdown> {
         .map((language) => DropdownMenuItem<Language>(
             value: language,
             child: widget.itemBuilder != null
-                ? widget.itemBuilder(language)
+                ? widget.itemBuilder!(language)
                 : _buildDefaultMenuItem(language)))
         .toList();
 
@@ -69,8 +69,8 @@ class _LanguagePickerDropdownState extends State<LanguagePickerDropdown> {
             isDense: true,
             onChanged: (value) {
               setState(() {
-                _selectedLanguage = value;
-                widget.onValuePicked(value);
+                _selectedLanguage = value!;
+                widget.onValuePicked!(value);
               });
             },
             items: items,

lib/languages.dart

@@ -5,8 +5,8 @@ class Language {
   final String isoCode;
 
   Language.fromMap(Map<String, String> map)
-      : name = map['name'],
-        isoCode = map['isoCode'];
+      : name = map['name']!,
+        isoCode = map['isoCode']!;
 }
 
 final List defaultLanguagesList = [