added logic to save collections and display them

lib/pages/collections_page.dart

@@ -1,5 +1,7 @@
 import 'package:flutter/material.dart';
 
+import '../model/collection.dart';
+import '../service/storage.dart';
 import '../widgets/create_bookmark_collection_dialog.dart';
 
 class CollectionsPage extends StatefulWidget {
@@ -11,23 +13,36 @@ class CollectionsPage extends StatefulWidget {
 }
 
 class _CollectionsPageState extends State<CollectionsPage> {
+  final collections = Storage.loadCollections();
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(
       appBar: AppBar(),
       floatingActionButton: FloatingActionButton(
-        onPressed: () => showDialog(
-          context: context,
-          builder: (context) => CreateBookmarkCollectionDialog(),
-        ),
+        onPressed: onAddButtonPressed,
         child: Icon(Icons.add),
       ),
-      body: ListView(),
+      body: ListView.builder(
+        itemBuilder: itemBuilder,
+        itemCount: collections.length,
+      ),
     );
   }
 
   void onAddButtonPressed() => showDialog(
     context: context,
-    builder: (context) => CreateBookmarkCollectionDialog(),
+    builder: (context) =>
+        CreateBookmarkCollectionDialog(onSavePressed: onCollectionSaved),
   );
+
+  void onCollectionSaved(String name) {
+    collections.add(Collection(name: name));
+    setState(() {});
+    Storage.saveCollections(collections);
+  }
+
+  Widget itemBuilder(BuildContext context, int index) {
+    return ListTile(title: Text(collections.elementAt(index).name));
+  }
 }

lib/widgets/create_bookmark_collection_dialog.dart

@@ -2,13 +2,19 @@ import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
 class CreateBookmarkCollectionDialog extends StatelessWidget {
-  const CreateBookmarkCollectionDialog({super.key});
+  const CreateBookmarkCollectionDialog({
+    super.key,
+    required this.onSavePressed,
+  });
+  final void Function(String name) onSavePressed;
 
   @override
   Widget build(BuildContext context) {
+    final nameController = TextEditingController();
     return AlertDialog(
       title: Text('Create Collection'),
       content: TextField(
+        controller: nameController,
         autofocus: true,
         maxLines: 1,
         maxLength: 50,
@@ -22,7 +28,13 @@ class CreateBookmarkCollectionDialog extends StatelessWidget {
         ),
       ),
       actions: [
-        FloatingActionButton(onPressed: () {}, child: Icon(Icons.save)),
+        FloatingActionButton(
+          onPressed: () {
+            onSavePressed(nameController.text);
+            Navigator.of(context).pop();
+          },
+          child: Icon(Icons.save),
+        ),
       ],
     );
   }