diff --git a/example/pubspec.lock b/example/pubspec.lock
index 299279a..88db764 100644
--- a/example/pubspec.lock
+++ b/example/pubspec.lock
@@ -164,7 +164,7 @@ packages:
       path: ".."
       relative: true
     source: path
-    version: "0.1.3"
+    version: "1.0.0-nullsafety.0"
   sky_engine:
     dependency: transitive
     description: flutter
diff --git a/lib/src/builders/dio_error_builder.dart b/lib/src/builders/dio_error_builder.dart
index 31aac61..5ceddce 100644
--- a/lib/src/builders/dio_error_builder.dart
+++ b/lib/src/builders/dio_error_builder.dart
@@ -5,42 +5,34 @@ import 'package:power_logger/src/view/dio_error_view.dart';
 ///Dio Error builder
 class DioErrorBuilder extends StatefulWidget {
   final DioError data;
-  DioErrorBuilder({Key key, @required this.data}) : super(key: key);
+  DioErrorBuilder({Key? key, required this.data}) : super(key: key);
 
   @override
   _DioErrorBuilderState createState() => _DioErrorBuilderState();
 }
 
 class _DioErrorBuilderState extends State<DioErrorBuilder> {
-  RequestOptions get _request => widget?.data?.requestOptions;
+  RequestOptions get _request => widget.data.requestOptions;
 
   String renderErrText(DioErrorType type) {
     switch (type) {
       case DioErrorType.connectTimeout:
         return '连接超时';
-        break;
       case DioErrorType.sendTimeout:
         return '发送超时';
-        break;
       case DioErrorType.receiveTimeout:
         return '接收超时';
-        break;
       case DioErrorType.response:
         return 'Serve Side Error';
-        break;
       case DioErrorType.cancel:
         return '取消连接';
-        break;
       case DioErrorType.other:
         return '未知错误';
-        break;
     }
-    return '';
   }
 
   @override
   Widget build(BuildContext context) {
-    if (widget.data == null) return ListTile(title: Text('NULL Dio Error'));
     return Material(
       color: Colors.red[100],
       child: Column(
diff --git a/lib/src/builders/dio_responses_builder.dart b/lib/src/builders/dio_responses_builder.dart
index 26cc94e..61b2280 100644
--- a/lib/src/builders/dio_responses_builder.dart
+++ b/lib/src/builders/dio_responses_builder.dart
@@ -5,14 +5,14 @@ import 'package:power_logger/src/view/dio_response_view.dart';
 /// Dio Response Builder
 class DioResponseBuilder extends StatefulWidget {
   final Response data;
-  DioResponseBuilder({Key key, this.data}) : super(key: key);
+  DioResponseBuilder({Key? key,required this.data}) : super(key: key);
 
   @override
   _DioResponseBuilderState createState() => _DioResponseBuilderState();
 }
 
 class _DioResponseBuilderState extends State<DioResponseBuilder> {
-  RequestOptions get _request => widget?.data?.requestOptions;
+  RequestOptions? get _request => widget.data.requestOptions;
 
   @override
   Widget build(BuildContext context) {
@@ -27,7 +27,7 @@ class _DioResponseBuilderState extends State<DioResponseBuilder> {
           ),
         ),
         title: Text(
-          _request.path,
+          _request!.path,
           style: TextStyle(
             color: Colors.black87,
           ),
@@ -37,7 +37,7 @@ class _DioResponseBuilderState extends State<DioResponseBuilder> {
           children: [
             Chip(
               backgroundColor: Colors.green.withOpacity(0.8),
-              label: Text(_request.method),
+              label: Text(_request!.method),
             ),
           ],
         ),
diff --git a/lib/src/data/logger_data.dart b/lib/src/data/logger_data.dart
index a92f9c9..c6bc464 100644
--- a/lib/src/data/logger_data.dart
+++ b/lib/src/data/logger_data.dart
@@ -13,7 +13,7 @@ class LoggerData {
 
   /// set the logger max number.
   static setMax(int max) {
-    _maxLength = max ?? 100;
+    _maxLength = max;
   }
 
   /// add data to logger
@@ -35,12 +35,12 @@ class LoggerData {
 
   /// add data listener
   static addListener(Function listener) {
-    _listenableData.addListener(listener);
+    _listenableData.addListener(listener as void Function());
   }
 
   /// remove data listener
   static removeListener(Function listener) {
-    _listenableData.removeListener(listener);
+    _listenableData.removeListener(listener as void Function());
   }
 }
 
diff --git a/lib/src/parser/dio_parser/dio_parser.dart b/lib/src/parser/dio_parser/dio_parser.dart
index 6739c03..69db2ff 100644
--- a/lib/src/parser/dio_parser/dio_parser.dart
+++ b/lib/src/parser/dio_parser/dio_parser.dart
@@ -15,20 +15,20 @@ enum ContentType {
 
 /// Dio parse
 class DioParser {
-  Response _response;
-  DioParser(Response response) {
+  Response? _response;
+  DioParser(Response? response) {
     _response = response;
   }
 
   /// get dio request
-  RequestOptions get request => _response.requestOptions;
+  RequestOptions get request => _response!.requestOptions;
 
   /// get dio response
-  Response get response => _response;
+  Response? get response => _response;
 
   /// get dio contentType
   ContentType get type {
-    String _ctype = response.headers.map['content-type'].first;
+    String _ctype = response!.headers.map['content-type']!.first;
     switch (_ctype) {
       case 'text/plain':
         return ContentType.TEXT_PLAIN;
diff --git a/lib/src/parser/unfocus_parser.dart b/lib/src/parser/unfocus_parser.dart
index 12f2f8b..70ddbc2 100644
--- a/lib/src/parser/unfocus_parser.dart
+++ b/lib/src/parser/unfocus_parser.dart
@@ -3,7 +3,7 @@ import 'package:flutter/material.dart';
 /// UnfocusParser
 class UnfocusParser extends StatelessWidget {
   final dynamic data;
-  const UnfocusParser({Key key, @required this.data}) : super(key: key);
+  const UnfocusParser({Key? key, required this.data}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {
diff --git a/lib/src/power_logger.dart b/lib/src/power_logger.dart
index 00306ba..0f18b15 100644
--- a/lib/src/power_logger.dart
+++ b/lib/src/power_logger.dart
@@ -26,14 +26,14 @@ class PowerLogger {
   ///PowerLogger.start(context,debug:true);
   ///```
   static start(BuildContext context, {bool debug = true}) {
-    WidgetsBinding.instance.addPostFrameCallback((_) {
+    WidgetsBinding.instance!.addPostFrameCallback((_) {
       PowerLogger.debug = debug;
       if (debug) _insertToOverlay(context);
     });
   }
 
   static _insertToOverlay(BuildContext context) {
-    Overlay.of(context).insert(OverlayEntry(
+    Overlay.of(context)!.insert(OverlayEntry(
       builder: (context) {
         return LoggerFab();
       },
diff --git a/lib/src/power_logger_view.dart b/lib/src/power_logger_view.dart
index f505e04..eb76785 100644
--- a/lib/src/power_logger_view.dart
+++ b/lib/src/power_logger_view.dart
@@ -6,7 +6,7 @@ import 'package:power_logger/src/views/settings_view.dart';
 
 ///Logger view
 class PowerLoggerView extends StatefulWidget {
-  PowerLoggerView({Key key}) : super(key: key);
+  PowerLoggerView({Key? key}) : super(key: key);
 
   @override
   _PowerLoggerViewState createState() => _PowerLoggerViewState();
@@ -15,7 +15,7 @@ class PowerLoggerView extends StatefulWidget {
 class _PowerLoggerViewState extends State<PowerLoggerView> {
   PageController _pageController = PageController();
   int _currentIndex = 0;
-  void Function(void Function()) _setState;
+  void Function(void Function())? _setState;
   @override
   Widget build(BuildContext context) {
     return Theme(
@@ -37,7 +37,7 @@ class _PowerLoggerViewState extends State<PowerLoggerView> {
           controller: _pageController,
           onPageChanged: (index) {
             _currentIndex = index;
-            if (_setState != null) _setState(() {});
+            if (_setState != null) _setState!(() {});
           },
           children: [
             LoggerView(),
diff --git a/lib/src/view/box_view.dart b/lib/src/view/box_view.dart
index 07a23ca..1363e22 100644
--- a/lib/src/view/box_view.dart
+++ b/lib/src/view/box_view.dart
@@ -3,12 +3,12 @@ import 'package:flutter/material.dart';
 ///BoxView
 class BoxView extends StatelessWidget {
   final Widget title;
-  final Widget child;
-  final List<Widget> children;
+  final Widget? child;
+  final List<Widget>? children;
   const BoxView({
-    Key key,
+    Key? key,
     this.child,
-    @required this.title,
+    required this.title,
     this.children,
   })  : assert(child != null || children != null),
         super(key: key);
diff --git a/lib/src/view/dio_error_view.dart b/lib/src/view/dio_error_view.dart
index db8e520..a4ea5ea 100644
--- a/lib/src/view/dio_error_view.dart
+++ b/lib/src/view/dio_error_view.dart
@@ -6,7 +6,7 @@ import 'package:power_logger/src/view/title_view.dart';
 
 class DioErrorView extends StatefulWidget {
   final DioError data;
-  DioErrorView({Key key, @required this.data}) : super(key: key);
+  DioErrorView({Key? key, required this.data}) : super(key: key);
 
   @override
   _DioErrorViewState createState() => _DioErrorViewState();
@@ -15,7 +15,7 @@ class DioErrorView extends StatefulWidget {
 class _DioErrorViewState extends State<DioErrorView> {
   RequestOptions get _request => widget.data.requestOptions;
   _buildBaseURL() {
-    return _request.baseUrl == null || _request.baseUrl.length == 0
+    return _request.baseUrl.length == 0
         ? const SizedBox()
         : BoxView(
             title: Text('BaseURL'),
diff --git a/lib/src/view/dio_response_view.dart b/lib/src/view/dio_response_view.dart
index 543e8c1..9cac7da 100644
--- a/lib/src/view/dio_response_view.dart
+++ b/lib/src/view/dio_response_view.dart
@@ -14,8 +14,8 @@ import 'package:power_logger/src/view/title_view.dart';
 // enum
 
 class DioResponseView extends StatefulWidget {
-  final Response data;
-  DioResponseView({Key key, @required this.data}) : super(key: key);
+  final Response? data;
+  DioResponseView({Key? key, required this.data}) : super(key: key);
 
   @override
   _DioResponseViewState createState() => _DioResponseViewState();
@@ -24,9 +24,9 @@ class DioResponseView extends StatefulWidget {
 class _DioResponseViewState extends State<DioResponseView> {
   bool _showRawData = false;
   RequestOptions get _request => _dioParser.request;
-  DioParser _dioParser;
+  late DioParser _dioParser;
   _buildBaseURL() {
-    return _request.baseUrl == null || _request.baseUrl.length == 0
+    return _request.baseUrl.length == 0
         ? const SizedBox()
         : BoxView(
             title: Text('BaseURL'),
@@ -46,9 +46,9 @@ class _DioResponseViewState extends State<DioResponseView> {
       title: const Text('Status'),
       children: [
         Chip(
-          label: Text(widget.data.statusCode.toString()),
+          label: Text(widget.data!.statusCode.toString()),
         ),
-        Text(widget.data.statusMessage),
+        Text(widget.data!.statusMessage!),
       ],
     );
   }
@@ -77,7 +77,7 @@ class _DioResponseViewState extends State<DioResponseView> {
         return BoxView(
           title: Text('Data'),
           child: HighlightView(
-            widget.data.data,
+            widget.data!.data,
             language: _dioParser.highlight,
             theme: atomOneLightTheme,
           ),
@@ -85,9 +85,9 @@ class _DioResponseViewState extends State<DioResponseView> {
       case ContentType.JSON:
         //解析字符串类型的JSON.
         //parse json of String type.
-        if (widget.data.data is String) {
+        if (widget.data!.data is String) {
           String json = '';
-          json = prettyJson(jsonDecode(widget.data.data));
+          json = prettyJson(jsonDecode(widget.data!.data));
           return BoxView(
             title: Text('Data'),
             child: HighlightView(
@@ -100,12 +100,11 @@ class _DioResponseViewState extends State<DioResponseView> {
         return BoxView(
           title: Text('Data'),
           child: HighlightView(
-            prettyJson(widget.data.data),
+            prettyJson(widget.data!.data),
             language: 'json',
             theme: atomOneLightTheme,
           ),
         );
-        break;
       case ContentType.IMAGE:
         return Text("IMAGE");
       case ContentType.AUDIO:
@@ -118,7 +117,7 @@ class _DioResponseViewState extends State<DioResponseView> {
     return BoxView(
       title: Text('Data'),
       child: HighlightView(
-        prettyJson(widget.data.data),
+        prettyJson(widget.data!.data),
         language: 'json',
         theme: atomOneLightTheme,
       ),
@@ -128,7 +127,7 @@ class _DioResponseViewState extends State<DioResponseView> {
   _buildRawData() {
     return BoxView(
       title: Text('Raw Data'),
-      child: SelectableText(widget.data.data.toString()),
+      child: SelectableText(widget.data!.data.toString()),
     );
   }
 
@@ -152,10 +151,10 @@ class _DioResponseViewState extends State<DioResponseView> {
     return Scaffold(
       appBar: AppBar(
         backgroundColor: Colors.green[600],
-        title: Text(widget.data.requestOptions.path),
+        title: Text(widget.data!.requestOptions.path),
         actions: [
           Chip(
-            label: Text(widget.data.requestOptions.method),
+            label: Text(widget.data!.requestOptions.method),
             backgroundColor: Colors.lightGreen,
           ),
           SizedBox(width: 8),
@@ -171,7 +170,7 @@ class _DioResponseViewState extends State<DioResponseView> {
           _buildMap(_request.queryParameters),
           _buildMap(_request.data),
           TitleView(title: Text('Response')),
-          _buildMap(widget.data.headers.map),
+          _buildMap(widget.data!.headers.map),
           _buildStatus(),
           SwitchListTile(
             value: _showRawData,
diff --git a/lib/src/view/table_view.dart b/lib/src/view/table_view.dart
index b537811..2055bac 100644
--- a/lib/src/view/table_view.dart
+++ b/lib/src/view/table_view.dart
@@ -1,8 +1,8 @@
 import 'package:flutter/material.dart';
 
 class TableView extends StatelessWidget {
-  final Map map;
-  const TableView({Key key, @required this.map}) : super(key: key);
+  final Map? map;
+  const TableView({Key? key, required this.map}) : super(key: key);
   Widget _buildTableTitle(String title) {
     return Padding(
       padding: EdgeInsets.all(5),
diff --git a/lib/src/view/title_view.dart b/lib/src/view/title_view.dart
index a19b230..f70bc37 100644
--- a/lib/src/view/title_view.dart
+++ b/lib/src/view/title_view.dart
@@ -2,7 +2,7 @@ import 'package:flutter/material.dart';
 
 class TitleView extends StatelessWidget {
   final Widget title;
-  const TitleView({Key key, @required this.title}) : super(key: key);
+  const TitleView({Key? key, required this.title}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {
diff --git a/lib/src/views/info_view.dart b/lib/src/views/info_view.dart
index bb388af..f8ca8c7 100644
--- a/lib/src/views/info_view.dart
+++ b/lib/src/views/info_view.dart
@@ -8,7 +8,7 @@ import 'package:flutter/services.dart';
 import 'package:package_info/package_info.dart';
 
 class InfoView extends StatefulWidget {
-  InfoView({Key key}) : super(key: key);
+  InfoView({Key? key}) : super(key: key);
 
   @override
   _InfoViewState createState() => _InfoViewState();
@@ -16,9 +16,9 @@ class InfoView extends StatefulWidget {
 
 class _InfoViewState extends State<InfoView>
     with AutomaticKeepAliveClientMixin {
-  PackageInfo packageInfo;
-  AndroidDeviceInfo androidInfo;
-  IosDeviceInfo iosInfo;
+  PackageInfo? packageInfo;
+  AndroidDeviceInfo? androidInfo;
+  IosDeviceInfo? iosInfo;
 
   Future getAllInfo() async {
     DeviceInfoPlugin deviceInfo = DeviceInfoPlugin();
@@ -58,7 +58,7 @@ class _InfoViewState extends State<InfoView>
           children: [
             Text(title),
             AutoSizeText(
-              subTitle ?? '',
+              subTitle,
               style: TextStyle(fontSize: 26),
               maxLines: 2,
             ),
@@ -68,7 +68,7 @@ class _InfoViewState extends State<InfoView>
     );
   }
 
-  _buildTile(String title, String subTitle) {
+  _buildTile(String title, String? subTitle) {
     return DefaultTextStyle(
       style: TextStyle(color: Colors.black),
       child: ListTile(
@@ -93,53 +93,53 @@ class _InfoViewState extends State<InfoView>
   _buildAndroidList() {
     return SliverList(
         delegate: SliverChildListDelegate([
-      _buildTile('androidId', androidInfo.androidId),
-      _buildTile('board', androidInfo.board),
-      _buildTile('bootloader', androidInfo.bootloader),
-      _buildTile('brand', androidInfo.brand),
-      _buildTile('device', androidInfo.device),
-      _buildTile('display', androidInfo.display),
-      _buildTile('fingerprint', androidInfo.fingerprint),
-      _buildTile('hardware', androidInfo.hardware),
-      _buildTile('host', androidInfo.host),
-      _buildTile('id', androidInfo.id),
-      _buildTile('manufacturer', androidInfo.manufacturer),
-      _buildTile('model', androidInfo.model),
-      _buildTile('product', androidInfo.product),
-      _buildTile('tags', androidInfo.tags),
-      _buildTile('type', androidInfo.type),
-      _buildTile('isPhysicalDevice', androidInfo.isPhysicalDevice.toString()),
+      _buildTile('androidId', androidInfo!.androidId),
+      _buildTile('board', androidInfo!.board),
+      _buildTile('bootloader', androidInfo!.bootloader),
+      _buildTile('brand', androidInfo!.brand),
+      _buildTile('device', androidInfo!.device),
+      _buildTile('display', androidInfo!.display),
+      _buildTile('fingerprint', androidInfo!.fingerprint),
+      _buildTile('hardware', androidInfo!.hardware),
+      _buildTile('host', androidInfo!.host),
+      _buildTile('id', androidInfo!.id),
+      _buildTile('manufacturer', androidInfo!.manufacturer),
+      _buildTile('model', androidInfo!.model),
+      _buildTile('product', androidInfo!.product),
+      _buildTile('tags', androidInfo!.tags),
+      _buildTile('type', androidInfo!.type),
+      _buildTile('isPhysicalDevice', androidInfo!.isPhysicalDevice.toString()),
       _buildTile(
-          'supported32BitAbis', androidInfo.supported32BitAbis.join(',')),
+          'supported32BitAbis', androidInfo!.supported32BitAbis.join(',')),
       _buildTile(
-          'supported64BitAbis', androidInfo.supported64BitAbis.join(',')),
-      _buildTile('supportedAbis', androidInfo.supportedAbis.join(',')),
-      _buildTile('baseOS', androidInfo.version.baseOS),
-      _buildTile('codename', androidInfo.version.codename),
-      _buildTile('incremental', androidInfo.version.incremental),
-      _buildTile('release', androidInfo.version.release),
-      _buildTile('securityPatch', androidInfo.version.securityPatch),
-      _buildTile('previewSdkInt', androidInfo.version.previewSdkInt.toString()),
-      _buildTile('sdkInt', androidInfo.version.sdkInt.toString()),
-      _buildTile('systemFeatures', androidInfo.systemFeatures.join('\n')),
+          'supported64BitAbis', androidInfo!.supported64BitAbis.join(',')),
+      _buildTile('supportedAbis', androidInfo!.supportedAbis.join(',')),
+      _buildTile('baseOS', androidInfo!.version.baseOS),
+      _buildTile('codename', androidInfo!.version.codename),
+      _buildTile('incremental', androidInfo!.version.incremental),
+      _buildTile('release', androidInfo!.version.release),
+      _buildTile('securityPatch', androidInfo!.version.securityPatch),
+      _buildTile('previewSdkInt', androidInfo!.version.previewSdkInt.toString()),
+      _buildTile('sdkInt', androidInfo!.version.sdkInt.toString()),
+      _buildTile('systemFeatures', androidInfo!.systemFeatures.join('\n')),
     ]));
   }
 
   _buildIOSList() {
     return SliverList(
         delegate: SliverChildListDelegate([
-      _buildTile('identifierForVendor', iosInfo.identifierForVendor),
-      _buildTile('localizedModel', iosInfo.localizedModel),
-      _buildTile('model', iosInfo.model),
-      _buildTile('name', iosInfo.name),
-      _buildTile('systemName', iosInfo.systemName),
-      _buildTile('systemVersion', iosInfo.systemVersion),
-      _buildTile('isPhysicalDevice', iosInfo.isPhysicalDevice.toString()),
-      _buildTile('machine', iosInfo.utsname.machine),
-      _buildTile('nodename', iosInfo.utsname.nodename),
-      _buildTile('release', iosInfo.utsname.release),
-      _buildTile('sysname', iosInfo.utsname.sysname),
-      _buildTile('version', iosInfo.utsname.version),
+      _buildTile('identifierForVendor', iosInfo!.identifierForVendor),
+      _buildTile('localizedModel', iosInfo!.localizedModel),
+      _buildTile('model', iosInfo!.model),
+      _buildTile('name', iosInfo!.name),
+      _buildTile('systemName', iosInfo!.systemName),
+      _buildTile('systemVersion', iosInfo!.systemVersion),
+      _buildTile('isPhysicalDevice', iosInfo!.isPhysicalDevice.toString()),
+      _buildTile('machine', iosInfo!.utsname.machine),
+      _buildTile('nodename', iosInfo!.utsname.nodename),
+      _buildTile('release', iosInfo!.utsname.release),
+      _buildTile('sysname', iosInfo!.utsname.sysname),
+      _buildTile('version', iosInfo!.utsname.version),
     ]));
   }
 
@@ -171,10 +171,10 @@ class _InfoViewState extends State<InfoView>
                   mainAxisSpacing: 10,
                   crossAxisSpacing: 10,
                   children: [
-                    _buildGridItem('appName', packageInfo.appName),
-                    _buildGridItem('buildNumber', packageInfo.buildNumber),
-                    _buildGridItem('packageName', packageInfo.packageName),
-                    _buildGridItem('version', packageInfo.version),
+                    _buildGridItem('appName', packageInfo!.appName),
+                    _buildGridItem('buildNumber', packageInfo!.buildNumber),
+                    _buildGridItem('packageName', packageInfo!.packageName),
+                    _buildGridItem('version', packageInfo!.version),
                   ],
                 ),
               ),
diff --git a/lib/src/views/logger_view.dart b/lib/src/views/logger_view.dart
index f6a63c5..221d5a6 100644
--- a/lib/src/views/logger_view.dart
+++ b/lib/src/views/logger_view.dart
@@ -3,7 +3,7 @@ import 'package:power_logger/src/data/logger_data.dart';
 import 'package:power_logger/src/parser/data_parser.dart';
 
 class LoggerView extends StatefulWidget {
-  LoggerView({Key key}) : super(key: key);
+  LoggerView({Key? key}) : super(key: key);
 
   @override
   _LoggerViewState createState() => _LoggerViewState();
diff --git a/lib/src/views/settings_view.dart b/lib/src/views/settings_view.dart
index 00dbff0..22c1feb 100644
--- a/lib/src/views/settings_view.dart
+++ b/lib/src/views/settings_view.dart
@@ -1,7 +1,7 @@
 import 'package:flutter/material.dart';
 
 class SettingsView extends StatefulWidget {
-  SettingsView({Key key}) : super(key: key);
+  SettingsView({Key? key}) : super(key: key);
 
   @override
   _SettingsViewState createState() => _SettingsViewState();
diff --git a/lib/src/widgets/logger_fab.dart b/lib/src/widgets/logger_fab.dart
index bd50fcf..5fd3ca9 100644
--- a/lib/src/widgets/logger_fab.dart
+++ b/lib/src/widgets/logger_fab.dart
@@ -3,7 +3,7 @@ import 'package:flutter/physics.dart';
 import 'package:power_logger/src/power_logger_view.dart';
 
 class LoggerFab extends StatefulWidget {
-  LoggerFab({Key key}) : super(key: key);
+  LoggerFab({Key? key}) : super(key: key);
 
   @override
   _LoggerFabState createState() => _LoggerFabState();
@@ -12,9 +12,9 @@ class LoggerFab extends StatefulWidget {
 class _LoggerFabState extends State<LoggerFab>
     with SingleTickerProviderStateMixin {
   bool showSubPage = false;
-  AnimationController _animationController;
+  AnimationController? _animationController;
   var _dragAlignment = Alignment.center;
-  Animation<Alignment> _animation;
+  late Animation<Alignment> _animation;
   final _spring =
       const SpringDescription(mass: 15, stiffness: 1000, damping: 0.7);
 
@@ -34,7 +34,7 @@ class _LoggerFabState extends State<LoggerFab>
       calcAlignment = Alignment(calcAlignment.x, 0.9);
     if (_dragAlignment.y <= -0.9)
       calcAlignment = Alignment(calcAlignment.x, -0.9);
-    _animation = _animationController.drive(
+    _animation = _animationController!.drive(
       AlignmentTween(
         begin: _dragAlignment,
         end: calcAlignment,
@@ -44,7 +44,7 @@ class _LoggerFabState extends State<LoggerFab>
     final simulation =
         SpringSimulation(_spring, 0, 1, _normalizeVelocity(velocity, size));
 
-    _animationController.animateWith(simulation);
+    _animationController!.animateWith(simulation);
   }
 
   @override
@@ -69,7 +69,7 @@ class _LoggerFabState extends State<LoggerFab>
         duration: Duration(milliseconds: 300),
         opacity: showSubPage ? 0 : 1,
         child: GestureDetector(
-          onPanStart: (details) => _animationController.stop(canceled: true),
+          onPanStart: (details) => _animationController!.stop(canceled: true),
           onPanUpdate: (details) => setState(() => _dragAlignment += Alignment(
                 details.delta.dx / (size.width / 2),
                 details.delta.dy / (size.height / 2),
@@ -94,7 +94,7 @@ class _LoggerFabState extends State<LoggerFab>
 }
 
 class _FabButton extends StatelessWidget {
-  const _FabButton({Key key}) : super(key: key);
+  const _FabButton({Key? key}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {
diff --git a/pubspec.yaml b/pubspec.yaml
index 3ad6247..7bbb22c 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,10 +1,10 @@
 name: power_logger
 description: A well log tool on flutter, support Dio and custom type data.
-version: 0.1.3
+version: 1.0.0-nullsafety.0
 homepage: https://github.com/laiiihz/power_logger
 
 environment:
-  sdk: ">=2.7.0 <3.0.0"
+  sdk: '>=2.12.0 <3.0.0'
   flutter: ">=1.17.0"
 
 dependencies: