added minimal error handling and user feedback

lib/l10n/app_de.arb

@@ -30,8 +30,14 @@
     "import": "Importieren",
     "activateJsonExport": "Immer als JSON speichern",
 
+    "@@comment": "Info",
+    "exportSuccess": "Daten exportiert",
+    "importSuccess": "Daten importiert",
+
     "@@comment": "Errors",
     "errorStoragePermisson": "Zugriff auf Speicher verwehrt",
     "errorCouldNotLaunchUrl": "Konnte Url nicht öffnen",
-    "errorInvalidUrl": "Fehlerhafte Url"
+    "errorInvalidUrl": "Fehlerhafte Url",
+    "exportFailed": "Export fehlgeschlagen",
+    "importFailed": "Import fehlgeschlagen"
 }

lib/l10n/app_en.arb

@@ -30,8 +30,15 @@
     "import": "Import",
     "activateJsonExport": "Always save to JSON",
 
+    
+    "@@comment": "Info",
+    "exportSuccess": "Exported data",
+    "importSuccess": "Imported data",
+    
     "@@comment": "Errors",
     "errorStoragePermisson": "Storage permissions denied",
     "errorCouldNotLaunchUrl": "Could not launch Url",
-    "errorInvalidUrl": "Invalid Url"
+    "errorInvalidUrl": "Invalid Url",
+    "exportFailed": "Export failed",
+    "importFailed": "Import failed"
 }

lib/pages/settings_page.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:flutter/material.dart';
 import 'package:permission_handler/permission_handler.dart';
 
@@ -43,20 +45,42 @@ class _SettingsPageState extends State<SettingsPage> {
   }
 
   void onActivateJsonExportPressed() async {
-    if (await checkStoragePermission) Storage.exportToJsonFile();
+    if (!await checkStoragePermission) return;
+
+    Storage.exportToJsonFile().then(showExportInfo);
   }
 
   void onActivateJsonImportPressed() async {
-    if (await checkStoragePermission) Storage.importFromJsonFile();
+    if (!await checkStoragePermission) return;
+    Storage.importFromJsonFile().then(showImportInfo);
   }
 
   Future<bool> get checkStoragePermission async {
     if (!(await PermissionService.requestStoragePermission).isGranted) {
       if (mounted) {
-        Notifying.showStoragePermissionErrorSnackbar(context);
+        Notifying.showErrorSnackbar(
+          context,
+          AppLocalizations.of(context)!.errorStoragePermisson,
+        );
         return false;
       }
     }
     return true;
   }
+
+  void showExportInfo(bool success) => Notifying.showSnackbar(
+    context,
+    text: success
+        ? AppLocalizations.of(context)!.exportSuccess
+        : AppLocalizations.of(context)!.exportFailed,
+    isError: success,
+  );
+
+  void showImportInfo(bool success) => Notifying.showSnackbar(
+    context,
+    text: success
+        ? AppLocalizations.of(context)!.importSuccess
+        : AppLocalizations.of(context)!.importFailed,
+    isError: success,
+  );
 }

lib/service/json_file_service.dart

@@ -13,48 +13,56 @@ class JsonFileService {
     required List<Collection> collections,
     required List<Bookmark> bookmarks,
   }) async {
-    final dir = await _directoryPath;
+    try {
+      final dir = await _directoryPath;
+      if (dir.isEmpty) return false;
 
-    final data = {
-      'collections': collections.map((c) => c.toJson()).toList(),
-      'bookmarks': bookmarks.map((b) => b.toJson()).toList(),
-    };
-    final json = jsonEncode(data).codeUnits;
-    final file = XFile.fromData(
-      Uint8List.fromList(json),
-      mimeType: 'application/json',
-      name: constants.jsonFileName,
-    );
-
-    file.saveTo('$dir/${constants.jsonFileName}');
+      final data = {
+        'collections': collections.map((c) => c.toJson()).toList(),
+        'bookmarks': bookmarks.map((b) => b.toJson()).toList(),
+      };
+      final json = jsonEncode(data).codeUnits;
+      final file = XFile.fromData(
+        Uint8List.fromList(json),
+        mimeType: 'application/json',
+        name: constants.jsonFileName,
+      );
 
+      file.saveTo('$dir/${constants.jsonFileName}');
+    } catch (e) {
+      return false;
+    }
     return false;
   }
 
   static Future<({List<Collection> collections, List<Bookmark> bookmarks})>
   importFromJson() async {
-    const typeGroup = XTypeGroup(label: 'json', extensions: <String>['json']);
-    final XFile? file = await openFile(
-      acceptedTypeGroups: <XTypeGroup>[typeGroup],
-    );
+    try {
+      const typeGroup = XTypeGroup(label: 'json', extensions: <String>['json']);
+      final XFile? file = await openFile(
+        acceptedTypeGroups: <XTypeGroup>[typeGroup],
+      );
 
-    if (file == null) {
+      if (file == null) {
+        return (collections: <Collection>[], bookmarks: <Bookmark>[]);
+      }
+
+      final jsonString = await file.readAsString();
+
+      final data = jsonDecode(jsonString) as Map<String, dynamic>;
+
+      final collections = (data['collections'] as List<dynamic>? ?? [])
+          .map((json) => Collection.fromJson(json as Map<String, dynamic>))
+          .toList();
+
+      final bookmarks = (data['bookmarks'] as List<dynamic>? ?? [])
+          .map((json) => Bookmark.fromJson(json as Map<String, dynamic>))
+          .toList();
+
+      return (collections: collections, bookmarks: bookmarks);
+    } catch (e) {
       return (collections: <Collection>[], bookmarks: <Bookmark>[]);
     }
-
-    final jsonString = await file.readAsString();
-
-    final data = jsonDecode(jsonString) as Map<String, dynamic>;
-
-    final collections = (data['collections'] as List<dynamic>? ?? [])
-        .map((json) => Collection.fromJson(json as Map<String, dynamic>))
-        .toList();
-
-    final bookmarks = (data['bookmarks'] as List<dynamic>? ?? [])
-        .map((json) => Bookmark.fromJson(json as Map<String, dynamic>))
-        .toList();
-
-    return (collections: collections, bookmarks: bookmarks);
   }
 
   static Future<String> get _directoryPath async {

lib/service/notifying.dart

@@ -54,11 +54,11 @@ class Notifying {
     showSnackbar(context, text: errorText, isError: true);
   }
 
-  static void showStoragePermissionErrorSnackbar(BuildContext context) {
-    showSnackbar(
-      context,
-      text: AppLocalizations.of(context)!.errorStoragePermisson,
-      isError: true,
-    );
+  static void showErrorSnackbar(BuildContext context, String message) {
+    showSnackbar(context, text: message, isError: true);
+  }
+
+  static void showMessageSnackbar(BuildContext context, String message) {
+    showSnackbar(context, text: message, isError: false);
   }
 }