Bumped minimum dart sdk constraint to 2.17.1 from 2.7.0

Added minimum flutter sdk constraint (3.0.0) Migrated all code to null safety and fixed all warnings

Author: VarunS2002

sudoku/lib/alerts.dart

@@ -11,7 +11,7 @@ class AlertGameOver extends StatelessWidget {
  static bool newGame = false;
  static bool restartGame = false;
 
- const AlertGameOver({Key key}) : super(key: key);
+ const AlertGameOver({Key? key}) : super(key: key);
 
  @override
  Widget build(BuildContext context) {
@@ -56,24 +56,25 @@ class AlertGameOver extends StatelessWidget {
 class AlertDifficultyState extends StatefulWidget {
  String currentDifficultyLevel;
 
- AlertDifficultyState(this.currentDifficultyLevel, {Key key})
+ AlertDifficultyState(this.currentDifficultyLevel, {Key? key})
  : super(key: key);
 
  @override
  // ignore: no_logic_in_create_state
  AlertDifficulty createState() => AlertDifficulty(currentDifficultyLevel);
 
- static String get difficulty {
+ static String? get difficulty {
  return AlertDifficulty.difficulty;
  }
 
- static set difficulty(String level) {
+ static set difficulty(String? level) {
  AlertDifficulty.difficulty = level;
  }
 }
 
 class AlertDifficulty extends State<AlertDifficultyState> {
- static String difficulty;
+ // ignore: avoid_init_to_null
+ static String? difficulty = null;
  static final List<String> difficulties = [
  'beginner',
  'easy',
@@ -120,7 +121,7 @@ class AlertDifficulty extends State<AlertDifficultyState> {
 }
 
 class AlertExit extends StatelessWidget {
- const AlertExit({Key key}) : super(key: key);
+ const AlertExit({Key? key}) : super(key: key);
 
  @override
  Widget build(BuildContext context) {
@@ -164,23 +165,24 @@ class AlertExit extends StatelessWidget {
 }
 
 class AlertNumbersState extends StatefulWidget {
- const AlertNumbersState({Key key}) : super(key: key);
+ const AlertNumbersState({Key? key}) : super(key: key);
 
  @override
  AlertNumbers createState() => AlertNumbers();
 
- static int get number {
+ static int? get number {
  return AlertNumbers.number;
  }
 
- static set number(int number) {
+ static set number(int? number) {
  AlertNumbers.number = number;
  }
 }
 
 class AlertNumbers extends State<AlertNumbersState> {
- static int number;
- int numberSelected;
+ // ignore: avoid_init_to_null
+ static int? number = null;
+ late int numberSelected;
  static final List<int> numberList1 = [1, 2, 3];
  static final List<int> numberList2 = [4, 5, 6];
  static final List<int> numberList3 = [7, 8, 9];
@@ -263,13 +265,13 @@ class AlertNumbers extends State<AlertNumbersState> {
 class AlertAccentColorsState extends StatefulWidget {
  String currentAccentColor;
 
- AlertAccentColorsState(this.currentAccentColor, {Key key}) : super(key: key);
+ AlertAccentColorsState(this.currentAccentColor, {Key? key}) : super(key: key);
 
- static String get accentColor {
+ static String? get accentColor {
  return AlertAccentColors.accentColor;
  }
 
- static set accentColor(String color) {
+ static set accentColor(String? color) {
  AlertAccentColors.accentColor = color;
  }
 
@@ -279,7 +281,8 @@ class AlertAccentColorsState extends StatefulWidget {
 }
 
 class AlertAccentColors extends State<AlertAccentColorsState> {
- static String accentColor;
+ // ignore: avoid_init_to_null
+ static String? accentColor = null;
  static final List<String> accentColors = [...Styles.accentColors.keys];
  String currentAccentColor;
 
@@ -329,7 +332,7 @@ class AlertAbout extends StatelessWidget {
  static const String licenseURL =
  "https://github.com/VarunS2002/Flutter-Sudoku/blob/master/LICENSE";
 
- const AlertAbout({Key key}) : super(key: key);
+ const AlertAbout({Key? key}) : super(key: key);
 
  openURL(String url) async {
  await launchUrl(Uri.parse(url), mode: LaunchMode.externalApplication);

sudoku/lib/main.dart

@@ -21,7 +21,7 @@ void main() {
 }
 
 class MyApp extends StatelessWidget {
- const MyApp({Key key}) : super(key: key);
+ const MyApp({Key? key}) : super(key: key);
 
  static const String versionNumber = '2.4.1';
 
@@ -39,7 +39,7 @@ class MyApp extends StatelessWidget {
 }
 
 class HomePage extends StatefulWidget {
- const HomePage({Key key}) : super(key: key);
+ const HomePage({Key? key}) : super(key: key);
 
  @override
  State<StatefulWidget> createState() => HomePageState();
@@ -50,13 +50,13 @@ class HomePageState extends State<HomePage> {
  bool gameOver = false;
  int timesCalled = 0;
  bool isButtonDisabled = false;
- List<List<List<int>>> gameList;
- List<List<int>> game;
- List<List<int>> gameCopy;
- List<List<int>> gameSolved;
- static String currentDifficultyLevel;
- static String currentTheme;
- static String currentAccentColor;
+ late List<List<List<int>>> gameList;
+ late List<List<int>> game;
+ late List<List<int>> gameCopy;
+ late List<List<int>> gameSolved;
+ static String? currentDifficultyLevel;
+ static String? currentTheme;
+ static String? currentAccentColor;
  static String platform = () {
  if (kIsWeb) {
  return 'web-${defaultTargetPlatform.toString().replaceFirst("TargetPlatform.", "").toLowerCase()}';
@@ -99,9 +99,9 @@ class HomePageState extends State<HomePage> {
  currentAccentColor = 'Blue';
  setPrefs('currentAccentColor');
  }
- newGame(currentDifficultyLevel);
+ newGame(currentDifficultyLevel!);
  changeTheme('set');
- changeAccentColor(currentAccentColor, true);
+ changeAccentColor(currentAccentColor!, true);
  });
  }
 
@@ -117,11 +117,11 @@ class HomePageState extends State<HomePage> {
  setPrefs(String property) async {
  final prefs = await SharedPreferences.getInstance();
  if (property == 'currentDifficultyLevel') {
- prefs.setString('currentDifficultyLevel', currentDifficultyLevel);
+ prefs.setString('currentDifficultyLevel', currentDifficultyLevel!);
  } else if (property == 'currentTheme') {
- prefs.setString('currentTheme', currentTheme);
+ prefs.setString('currentTheme', currentTheme!);
  } else if (property == 'currentAccentColor') {
- prefs.setString('currentAccentColor', currentAccentColor);
+ prefs.setString('currentAccentColor', currentAccentColor!);
  }
  }
 
@@ -157,10 +157,10 @@ class HomePageState extends State<HomePage> {
  void changeAccentColor(String color, [bool firstRun = false]) {
  setState(() {
  if (Styles.accentColors.keys.contains(color)) {
- Styles.primaryColor = Styles.accentColors[color];
+ Styles.primaryColor = Styles.accentColors[color]!;
  } else {
  currentAccentColor = 'Blue';
- Styles.primaryColor = Styles.accentColors[color];
+ Styles.primaryColor = Styles.accentColors[color]!;
  }
  if (color == 'Red') {
  Styles.secondaryColor = Styles.orange;
@@ -228,6 +228,11 @@ class HomePageState extends State<HomePage> {
  emptySquares = 54;
  }
  break;
+ default:
+ {
+ emptySquares = 2;
+ }
+ break;
  }
  SudokuGenerator generator = SudokuGenerator(emptySquares: emptySquares);
  return [generator.newSudoku, generator.newSudokuSolved];
@@ -281,7 +286,7 @@ class HomePageState extends State<HomePage> {
  if (Styles.primaryBackgroundColor == Styles.darkGrey) {
  color = Styles.grey;
  } else {
- color = Colors.grey[300];
+ color = Colors.grey[300]!;
  }
  } else {
  color = Styles.primaryBackgroundColor;
@@ -332,7 +337,7 @@ class HomePageState extends State<HomePage> {
  } else {
  emptyColor = Styles.secondaryColor;
  }
- List<SizedBox> buttonList = List<SizedBox>.filled(9, null);
+ List<SizedBox> buttonList = List<SizedBox>.filled(9, const SizedBox());
  for (var i = 0; i <= 8; i++) {
  var k = timesCalled;
  buttonList[i] = SizedBox(
@@ -403,14 +408,11 @@ class HomePageState extends State<HomePage> {
  }
 
  List<Row> createRows() {
- List<Row> rowList = List<Row>.filled(9, null);
- for (var i = 0; i <= 8; i++) {
- rowList[i] = oneRow();
- }
+ List<Row> rowList = List<Row>.generate(9, (i) => oneRow());
  return rowList;
  }
 
- void callback(List<int> index, int number) {
+ void callback(List<int> index, int? number) {
  setState(() {
  if (number == null) {
  return;
@@ -453,7 +455,7 @@ class HomePageState extends State<HomePage> {
  onTap: () {
  Navigator.pop(context);
  Timer(const Duration(milliseconds: 200),
- () => newGame(currentDifficultyLevel));
+ () => newGame(currentDifficultyLevel!));
  },
  ),
  ListTile(
@@ -480,7 +482,7 @@ class HomePageState extends State<HomePage> {
  duration: const Duration(milliseconds: 350),
  context: outerContext,
  builder: (_) => AlertDifficultyState(
- currentDifficultyLevel)).whenComplete(() {
+ currentDifficultyLevel!)).whenComplete(() {
  if (AlertDifficultyState.difficulty != null) {
  Timer(const Duration(milliseconds: 300), () {
  newGame(
@@ -519,7 +521,7 @@ class HomePageState extends State<HomePage> {
  duration: const Duration(milliseconds: 350),
  context: outerContext,
  builder: (_) => AlertAccentColorsState(
- currentAccentColor)).whenComplete(() {
+ currentAccentColor!)).whenComplete(() {
  if (AlertAccentColorsState.accentColor != null) {
  Timer(const Duration(milliseconds: 300), () {
  currentAccentColor =

sudoku/lib/material_color_generator.dart

@@ -5,7 +5,7 @@ import 'package:flutter/material.dart';
 MaterialColor createMaterialColor(String hexColorCode) {
  Color color = Color(int.parse("0xFF$hexColorCode"));
  List strengths = <double>[.05];
- Map swatch = <int, Color>{};
+ Map<int, Color> swatch = {};
  final int r = color.red, g = color.green, b = color.blue;
 
  for (int i = 1; i < 10; i++) {

sudoku/lib/splash_screen_page.dart

@@ -5,7 +5,7 @@ import 'main.dart';
 import 'styles.dart';
 
 class SplashScreenPage extends StatefulWidget {
- const SplashScreenPage({Key key}) : super(key: key);
+ const SplashScreenPage({Key? key}) : super(key: key);
 
  @override
  SplashScreenPageState createState() => SplashScreenPageState();
@@ -21,7 +21,7 @@ class SplashScreenPageState extends State<SplashScreenPage> {
  Widget build(BuildContext context) {
  return SplashScreen(
  seconds: 2,
- navigateAfterSeconds: HomePage(),
+ navigateAfterSeconds: const HomePage(),
  title: Text(
  '\nSudoku',
  style: TextStyle(

sudoku/pubspec.lock

@@ -486,5 +486,5 @@ packages:
  source: hosted
  version: "3.1.1"
 sdks:
- dart: ">=2.17.0 <3.0.0"
- flutter: ">=2.10.0"
+ dart: ">=2.17.1 <3.0.0"
+ flutter: ">=3.0.0"

sudoku/pubspec.yaml

@@ -18,7 +18,8 @@ publish_to: 'none' # Remove this line if you wish to publish to pub.dev
 version: 2.4.1+2041
 
 environment:
- sdk: ">=2.7.0 <3.0.0"
+ sdk: ">=2.17.1 <3.0.0"
+ flutter: ">=3.0.0"
 
 # Dependencies specify other packages that your package needs in order to work.
 # To automatically upgrade your package dependencies to the latest versions