我知道有很多问题的标题类似 NoSuchMethodError: The method '#**something**#' was called on null.通常当您尝试访问空对象的方法时会发生此问题。但是，就我而言，当我尝试将以下代码添加到我的 StatefulWidget 时会显示此异常:
_handleMyBusinessesTap() {
Navigator.of(context).push(
MaterialPageRoute(
builder: (context) => PageBusinessList(
firebaseUser: widget.firebaseUser,
),
),
);
}
一旦我尝试在我的代码中使用 Navigator 对象，我就会收到此异常。
我能想到的我在此页面中与 Navigator 对象不会导致任何问题的其他页面的唯一区别是我以这种方式构建我的页面:
Widget build(BuildContext context) {
return DefaultTabController(
length: 3,
child: Scaffold(
appBar: _buildAppBar(),
drawer: _buildDrawer(),
body: _buildBody(),
),
);
}
我在这里使用
DefaultTabController包含 3 页的正文: Widget _buildBody() {
return TabBarView(
children: [
MyCardScreen(),
ReceivedScreen(),
SentScreen(),
],
);
}
_handleMyBusinessesTap方法是我在抽屉中的选项之一，我想带我到一个新页面，但是由于某种原因，一旦我添加它，它就会在标题中抛出这个异常。有人遇到过这个问题并且知道应该如何处理吗？这是 buildDrawer 方法:
Widget _buildDrawer() {
return Drawer(
child: ListView(
padding: EdgeInsets.zero,
children: <Widget>[
UserAccountsDrawerHeader(
accountName: _buildAccountNameWidget(),
accountEmail: _buildAccountEmailWidget(),
currentAccountPicture: _buildAccountCircleAvatar(),
),
ListTile(title: Text("My Default Business Card"), onTap: _handleMyDefaultBusinessCardTap()),
ListTile(title: Text("My Businesses"), onTap: _handleMyBusinessesTap()),
ListTile(title: Text("Terms and Conditions"), onTap: _handleTermsAndConditionsTap()),
ListTile(title: Text("Privacy Policy"), onTap: _handlePrivacyPolicyTap()),
ListTile(title: Text("Log Out"), onTap: _handleLogOutTap()),
],
),
);
}
这是堆栈的其余部分:
I/flutter ( 722): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter ( 722): The following assertion was thrown building PageMain(dirty, dependencies: [_InheritedTheme,
I/flutter ( 722): _LocalizationsScope-[GlobalKey#b039d]], state: _PageMainWidgetState#e33af):
I/flutter ( 722): setState() or markNeedsBuild() called during build.
I/flutter ( 722): This Overlay widget cannot be marked as needing to build because the framework is already in the
I/flutter ( 722): process of building widgets. A widget can be marked as needing to be built during the build phase
I/flutter ( 722): only if one of its ancestors is currently building. This exception is allowed because the framework
I/flutter ( 722): builds parent widgets before children, which means a dirty descendant will always be built.
I/flutter ( 722): Otherwise, the framework might not visit this widget during this build phase.
I/flutter ( 722): The widget on which setState() or markNeedsBuild() was called was:
I/flutter ( 722): Overlay-[LabeledGlobalKey<OverlayState>#51a6b](state: OverlayState#7d0ac(entries:
I/flutter ( 722): [OverlayEntry#f42cb(opaque: false; maintainState: false), OverlayEntry#d6b18(opaque: false;
I/flutter ( 722): maintainState: true), OverlayEntry#75d78(opaque: false; maintainState: false),
I/flutter ( 722): OverlayEntry#02406(opaque: false; maintainState: true), OverlayEntry#8f4e5(opaque: false;
I/flutter ( 722): maintainState: false), OverlayEntry#11c40(opaque: false; maintainState: true)]))
I/flutter ( 722): The widget which was currently being built when the offending call was made was:
I/flutter ( 722): PageMain(dirty, dependencies: [_InheritedTheme, _LocalizationsScope-[GlobalKey#b039d]], state:
I/flutter ( 722): _PageMainWidgetState#e33af)
I/flutter ( 722): When the exception was thrown, this was the stack:
I/flutter ( 722): #0 Element.markNeedsBuild.<anonymous closure> (package:flutter/src/widgets/framework.dart:3503:11)
I/flutter ( 722): #1 Element.markNeedsBuild (package:flutter/src/widgets/framework.dart:3529:6)
I/flutter ( 722): #2 State.setState (package:flutter/src/widgets/framework.dart:1133:14)
I/flutter ( 722): #3 OverlayState.insertAll (package:flutter/src/widgets/overlay.dart:346:5)
I/flutter ( 722): #4 OverlayRoute.install (package:flutter/src/widgets/routes.dart:43:24)
I/flutter ( 722): #5 TransitionRoute.install (package:flutter/src/widgets/routes.dart:180:11)
I/flutter ( 722): #6 ModalRoute.install (package:flutter/src/widgets/routes.dart:895:11)
I/flutter ( 722): #7 NavigatorState.push (package:flutter/src/widgets/navigator.dart:1742:11)
I/flutter ( 722): #8 _PageMainWidgetState._handleMyBusinessesTap (package:bizooc_client/pages/page_main.dart:86:27)
I/flutter ( 722): #9 _PageMainWidgetState._buildDrawer (package:bizooc_client/pages/page_main.dart:60:57)
I/flutter ( 722): #10 _PageMainWidgetState.build (package:bizooc_client/pages/page_main.dart:33:17)
I/flutter ( 722): #11 StatefulElement.build (package:flutter/src/widgets/framework.dart:3825:27)
I/flutter ( 722): #12 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3739:15)
I/flutter ( 722): #13 Element.rebuild (package:flutter/src/widgets/framework.dart:3565:5)
I/flutter ( 722): #14 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3722:5)
I/flutter ( 722): #15 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3864:11)
I/flutter ( 722): #16 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3717:5)
I/flutter ( 722): #17 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2961:14)
I/flutter ( 722): #18 Element.updateChild (package:flutter/src/widgets/framework.dart:2764:12)
I/flutter ( 722): #19 SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4876:14)
I/flutter ( 722): #20 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2961:14)
I/flutter ( 722): #21 Element.updateChild (package:flutter/src/widgets/framework.dart:2764:12)
I/flutter ( 722): #22 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3750:16)
I/flutter ( 722): #23 Element.rebuild (package:flutter/src/widgets/framework.dart:3565:5)
I/flutter ( 722): #24 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3722:5)
I/flutter ( 722): #25 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3717:5)
I/flutter ( 722): #26 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2961:14)
I/flutter ( 722): #27 Element.updateChild (package:flutter/src/widgets/framework.dart:2764:12)
I/flutter ( 722): #28 SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4876:14)
I/flutter ( 722): #29 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2961:14)
I/flutter ( 722): #30 Element.updateChild (package:flutter/src/widgets/framework.dart:2764:12)
I/flutter ( 722): #31 SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4876:14)
I/flutter ( 722): #32 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2961:14)
I/flutter ( 722): #33 Element.updateChild (package:flutter/src/widgets/framework.dart:2764:12)
I/flutter ( 722): #34 SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4876:14)
I/flutter ( 722): #35 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2961:14)
I/flutter ( 722): #36 Element.updateChild (package:flutter/src/widgets/framework.dart:2764:12)
I/flutter ( 722): #37 SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4876:14)
I/flutter ( 722): #38 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2961:14)
I/flutter ( 722): #39 Element.updateChild (package:flutter/src/widgets/framework.dart:2764:12)
I/flutter ( 722): #40 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3750:16)
I/flutter ( 722): #41 Element.rebuild (package:flutter/src/widgets/framework.dart:3565:5)
I/flutter ( 722): #42 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3722:5)
I/flutter ( 722): #43 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3864:11)
I/flutter ( 722): #44 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3717:5)
I/flutter ( 722): #45 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2961:14)
I/flutter ( 722): #46 Element.updateChild (package:flutter/src/widgets/framework.dart:2764:12)
I/flutter ( 722): #47 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3750:16)
I/flutter ( 722): #48 Element.rebuild (package:flutter/src/widgets/framework.dart:3565:5)
I/flutter ( 722): #49 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3722:5)
I/flutter ( 722): #50 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3717:5)
I/flutter ( 722): #51 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2961:14)
I/flutter ( 722): #52 Element.updateChild (package:flutter/src/widgets/framework.dart:2764:12)
I/flutter ( 722): #53 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3750:16)
I/flutter ( 722): #54 Element.rebuild (package:flutter/src/widgets/framework.dart:3565:5)
I/flutter ( 722): #55 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3722:5)
I/flutter ( 722): #56 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3864:11)
I/flutter ( 722): #57 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3717:5)
I/flutter ( 722): #58 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2961:14)
I/flutter ( 722): #59 Element.updateChild (package:flutter/src/widgets/framework.dart:2764:12)
I/flutter ( 722): #60 SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4876:14)
I/flutter ( 722): #61 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2961:14)
I/flutter ( 722): #62 Element.updateChild (package:flutter/src/widgets/framework.dart:2764:12)
I/flutter ( 722): #63 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3750:16)
I/flutter ( 722): #64 Element.rebuild (package:flutter/src/widgets/framework.dart:3565:5)
I/flutter ( 722): #65 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3722:5)
I/flutter ( 722): #66 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3717:5)
I/flutter ( 722): #67 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2961:14)
I/flutter ( 722): #68 Element.updateChild (package:flutter/src/widgets/framework.dart:2764:12)
I/flutter ( 722): #69 SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4876:14)
I/flutter ( 722): #70 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2961:14)
I/flutter ( 722): #71 Element.updateChild (package:flutter/src/widgets/framework.dart:2764:12)
I/flutter ( 722): #72 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3750:16)
I/flutter ( 722): #73 Element.rebuild (package:flutter/src/widgets/framework.dart:3565:5)
I/flutter ( 722): #74 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3722:5)
I/flutter ( 722): #75 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3864:11)
I/flutter ( 722): #76 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3717:5)
I/flutter ( 722): #77 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2961:14)
I/flutter ( 722): #78 Element.updateChild (package:flutter/src/widgets/framework.dart:2764:12)
I/flutter ( 722): #79 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3750:16)
I/flutter ( 722): #80 Element.rebuild (package:flutter/src/widgets/framework.dart:3565:5)
I/flutter ( 722): #81 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3722:5)
I/flutter ( 722): #82 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3717:5)
I/flutter ( 722): #83 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2961:14)
I/flutter ( 722): #84 Element.updateChild (package:flutter/src/widgets/framework.dart:2764:12)
I/flutter ( 722): #85 SingleChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:4876:14)
I/flutter ( 722): #86 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2961:14)
I/flutter ( 722): #87 Element.updateChild (package:flutter/src/widgets/framework.dart:2764:12)
I/flutter ( 722): #88 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3750:16)
I/flutter ( 722): #89 Element.rebuild (package:flutter/src/widgets/framework.dart:3565:5)
I/flutter ( 722): #90 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3722:5)
I/flutter ( 722): #91 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3717:5)
I/flutter ( 722): #92 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2961:14)
I/flutter ( 722): #93 Element.updateChild (package:flutter/src/widgets/framework.dart:2764:12)
I/flutter ( 722): #94 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3750:16)
I/flutter ( 722): #95 Element.rebuild (package:flutter/src/widgets/framework.dart:3565:5)
I/flutter ( 722): #96 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3722:5)
I/flutter ( 722): #97 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3864:11)
I/flutter ( 722): #98 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3717:5)
I/flutter ( 722): #99 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2961:14)
I/flutter ( 722): #100 Element.updateChild (package:flutter/src/widgets/framework.dart:2764:12)
I/flutter ( 722): #101 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3750:16)
I/flutter ( 722): #102 Element.rebuild (package:flutter/src/widgets/framework.dart:3565:5)
I/flutter ( 722): #103 ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:3722:5)
I/flutter ( 722): #104 StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:3864:11)
I/flutter ( 722): #105 ComponentElement.mount (package:flutter/src/widgets/framework.dart:3717:5)
I/flutter ( 722): #106 Element.inflateWidget (package:flutter/src/widgets/framework.dart:2961:14)
I/flutter ( 722): #107 Element.updateChild (package:flutter/src/widgets/framework.dart:2764:12)
I/flutter ( 722): #108 RenderObjectElement.updateChildren (package:flutter/src/widgets/framework.dart:4659:32)
I/flutter ( 722): #109 MultiChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4992:17)
I/flutter ( 722): #110 Element.updateChild (package:flutter/src/widgets/framework.dart:2753:15)
I/flutter ( 722): #111 _TheatreElement.update (package:flutter/src/widgets/overlay.dart:607:16)
I/flutter ( 722): #112 Element.updateChild (package:flutter/src/widgets/framework.dart:2753:15)
I/flutter ( 722): #113 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3750:16)
I/flutter ( 722): #114 Element.rebuild (package:flutter/src/widgets/framework.dart:3565:5)
I/flutter ( 722): #115 StatefulElement.update (package:flutter/src/widgets/framework.dart:3894:5)
I/flutter ( 722): #116 Element.updateChild (package:flutter/src/widgets/framework.dart:2753:15)
I/flutter ( 722): #117 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3750:16)
I/flutter ( 722): #118 Element.rebuild (package:flutter/src/widgets/framework.dart:3565:5)
I/flutter ( 722): #119 ProxyElement.update (package:flutter/src/widgets/framework.dart:4006:5)
I/flutter ( 722): #120 Element.updateChild (package:flutter/src/widgets/framework.dart:2753:15)
I/flutter ( 722): #121 SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4883:14)
I/flutter ( 722): #122 Element.updateChild (package:flutter/src/widgets/framework.dart:2753:15)
I/flutter ( 722): #123 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3750:16)
I/flutter ( 722): #124 Element.rebuild (package:flutter/src/widgets/framework.dart:3565:5)
I/flutter ( 722): #125 StatefulElement.update (package:flutter/src/widgets/framework.dart:3894:5)
I/flutter ( 722): #126 Element.updateChild (package:flutter/src/widgets/framework.dart:2753:15)
I/flutter ( 722): #127 SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4883:14)
I/flutter ( 722): #128 Element.updateChild (package:flutter/src/widgets/framework.dart:2753:15)
I/flutter ( 722): #129 SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:4883:14)
I/flutter ( 722): #130 Element.updateChild (package:flutter/src/widgets/framework.dart:2753:15)
I/flutter ( 722): #131 ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:3750:16)
I/flutter ( 722): #132 Element.rebuild (package:flutter/src/widgets/framework.dart:3565:5)
I/flutter ( 722): #133 BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2278:33)
I/flutter ( 722): #134 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding&WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:700:20)
I/flutter ( 722): #135 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:286:5)
I/flutter ( 722): #136 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1012:15)
I/flutter ( 722): #137 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:952:9)
I/flutter ( 722): #138 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:864:5)
I/flutter ( 722): #142 _invoke (dart:ui/hooks.dart:219:10)
I/flutter ( 722): #143 _drawFrame (dart:ui/hooks.dart:178:3)
I/flutter ( 722): (elided 3 frames from package dart:async)
I/flutter ( 722): ════════════════════════════════════════════════════════════════════════════════════════════════════
I/flutter ( 722): Another exception was thrown: NoSuchMethodError: The getter 'status' was called on null.
I/flutter ( 722): Another exception was thrown: NoSuchMethodError: The method 'drive' was called on null.
最佳答案
这是使用回调函数时的常见错误。
ListTile(title: Text("Log Out"), onTap: _handleLogOutTap()),
要解决您的问题，您有一些选择:
1-
ListTile(title: Text("Log Out"), onTap: _handleLogOutTap),
2-
ListTile(title: Text("Log Out"), onTap: () => _handleLogOutTap()),
3-
ListTile(title: Text("Log Out"), onTap: () { _handleLogOutTap() ; }),
您的所有
ListTile 都一样的。
关于flutter - NoSuchMethodError : The method 'drive' was called on null，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/56329987/