took care of compiler warnings

lib/add_form.dart

@@ -7,20 +7,17 @@ class AddForm extends StatefulWidget {
   final data.Page type;
 
   @override
-  State<StatefulWidget> createState() => _AddFormState(type);
+  State<StatefulWidget> createState() => _AddFormState();
 }
 
 class _AddFormState extends State<AddForm> {
-  _AddFormState(this.type);
   final _formKey = GlobalKey<FormState>();
-
-  final data.Page type;
   int _templatChoice = -1;
   String _listLabel = "";
   String _listDesc = "";
   List<data.List> templates = [];
 
-  final FocusNode _TemplateFocusNode = FocusNode();
+  final FocusNode _templateFocusNode = FocusNode();
 
   void loadTemplates() async {
     var rows = await DBHelper.dbHelper.getAllLists(data.Page.templates);
@@ -36,7 +33,7 @@ class _AddFormState extends State<AddForm> {
   List<DropdownMenuItem<int>> generateDropdown() {
     loadTemplates();
     List<DropdownMenuItem<int>> items = [
-      DropdownMenuItem<int>(child: Text("None"), value: -1)
+      const DropdownMenuItem<int>(child: Text("None"), value: -1)
     ];
     templates.asMap().forEach((index, value) {
       items.add(DropdownMenuItem<int>(
@@ -53,9 +50,9 @@ class _AddFormState extends State<AddForm> {
       appBar: AppBar(
         title: Text(
           'Add ' +
-              ((type == data.Page.lists)
+              ((widget.type == data.Page.lists)
                   ? 'Check List'
-                  : (type == data.Page.templates)
+                  : (widget.type == data.Page.templates)
                       ? 'Template'
                       : ''),
         ),
@@ -89,7 +86,7 @@ class _AddFormState extends State<AddForm> {
                 },
               ),
               DropdownButtonFormField<int>(
-                focusNode: _TemplateFocusNode,
+                focusNode: _templateFocusNode,
                 value: _templatChoice,
                 onChanged: (value) => setState(() {
                   _templatChoice = value!;
@@ -103,13 +100,13 @@ class _AddFormState extends State<AddForm> {
         ),
       ),
       floatingActionButton: FloatingActionButton(
-        child: Icon(Icons.save_alt),
+        child: const Icon(Icons.save_alt),
         onPressed: () async {
           if (_formKey.currentState!.validate()) {
             int id = await DBHelper.dbHelper.insertList(
               data.List(
                 _listLabel,
-                isTemplate: type.index == 1,
+                isTemplate: widget.type.index == 1,
                 description: _listDesc,
               ),
             );

lib/box_checker.dart

@@ -15,7 +15,7 @@ class BoxChecker extends StatelessWidget {
   Widget build(BuildContext context) {
     return MaterialApp(
       title: 'Flutter Demo',
-      theme: ThemeData.from(colorScheme: ColorScheme.dark()).copyWith(
+      theme: ThemeData.from(colorScheme: const ColorScheme.dark()).copyWith(
         canvasColor: Colors.blueGrey[900],
         cardColor: Colors.grey[800],
         scaffoldBackgroundColor: Colors.black12,

lib/check_list.dart

@@ -7,18 +7,16 @@ class CheckList extends StatefulWidget {
   final int id;
 
   @override
-  State<StatefulWidget> createState() => _CheckList(id);
+  State<StatefulWidget> createState() => _CheckList();
 }
 
 class _CheckList extends State<CheckList> {
-  _CheckList(this.id);
-  final int id;
   bool _editable = false;
   data.List? listData;
   List<data.Check> list = [];
 
   void _loadList() async {
-    var rows = await DBHelper.dbHelper.getList(id);
+    var rows = await DBHelper.dbHelper.getList(widget.id);
 
     list.clear();
     setState(() {
@@ -29,7 +27,7 @@ class _CheckList extends State<CheckList> {
   }
 
   void _loadListData() async {
-    var rows = await DBHelper.dbHelper.getListData(id);
+    var rows = await DBHelper.dbHelper.getListData(widget.id);
     listData = (rows.isNotEmpty) ? data.List.fromMap(rows[0]) : null;
   }
 
@@ -76,7 +74,8 @@ class _CheckList extends State<CheckList> {
       onTap: () => FocusScope.of(context).unfocus(),
       child: Scaffold(
         appBar: AppBar(
-          title: Text((listData != null) ? listData!.name : 'Check List: $id'),
+          title: Text(
+              (listData != null) ? listData!.name : 'Check List: ${widget.id}'),
           actions:
               (listData != null && listData!.isTemplate!) ? [iconButton()] : [],
         ),
@@ -128,7 +127,7 @@ class _CheckList extends State<CheckList> {
                   title: TextFormField(
                     enabled: (listData != null &&
                         (!listData!.isTemplate! || _editable)),
-                    decoration: InputDecoration(border: InputBorder.none),
+                    decoration: const InputDecoration(border: InputBorder.none),
                     initialValue: list[index].text,
                     onChanged: (value) {
                       list[index].text = value;
@@ -156,7 +155,8 @@ class _CheckList extends State<CheckList> {
             if (listData!.isTemplate! && !_editable) {
               ScaffoldMessenger.of(context)
                 ..clearSnackBars()
-                ..showSnackBar(SnackBar(content: Text("Template is locked")));
+                ..showSnackBar(
+                    const SnackBar(content: Text("Template is locked")));
               return;
             }
             _addItem();

lib/data_util.dart

@@ -9,9 +9,9 @@ class List {
   bool? isTemplate;
 
   Map<String, dynamic> toMap() {
-    var map = Map<String, dynamic>();
+    var map = <String, dynamic>{};
-    if (id != null) map["id"] = this.id;
+    if (id != null) map["id"] = id;
-    map["list_name"] = this.name;
+    map["list_name"] = name;
     if (description != null) map["list_desc"] = description;
     if (isTemplate != null) map["is_template"] = isTemplate! ? 1 : 0;
     return map;
@@ -36,11 +36,11 @@ class Check {
   int? listID;
 
   Map<String, dynamic> toMap() {
-    var map = Map<String, dynamic>();
+    var map = <String, dynamic>{};
-    if (id != null) map["id"] = this.id;
+    if (id != null) map["id"] = id;
-    map["check_text"] = this.text;
+    map["check_text"] = text;
-    map["status"] = this.value ? 1 : 0;
+    map["status"] = value ? 1 : 0;
-    if (listID != null) map["list_id"] = this.listID! as int;
+    if (listID != null) map["list_id"] = listID!;
     return map;
   }