Flutter debug模式下TabBarView里面列表显示正常，release模式下不显示

Question

Flutter debug模式下TabBarView里面列表显示正常，release模式下不显示

醉的不得了

10341622

发布于
2022-07-12

报"Null check operator used on a null value"
输出里面没有定位到main.dart哪行，都是框架里面的，有什么方法定位问题吗？

环境:
Windows11
Flutter 3.0.1
Getx 4.6.5

flutter run --release 控制台输出:

I/flutter (31177): Null check operator used on a null value
I/flutter (31177): #0      _PagePosition.applyViewportDimension (package:flutter/src/widgets/page_view.dart:455)
I/flutter (31177): #1      RenderViewport.performLayout (package:flutter/src/rendering/viewport.dart:1456)
I/flutter (31177): #2      RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #3      RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #4      RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #5      RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #6      RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #7      RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #8      RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #9      RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #10     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #11     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #12     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #13     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #14     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #15     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #16     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #17     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #18     RenderCustomPaint.performLayout (package:flutter/src/rendering/custom_paint.dart:545)
I/flutter (31177): #19     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #20     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #21     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #22     MultiChildLayoutDelegate.layoutChild (package:flutter/src/rendering/custom_layout.dart:171)
I/flutter (31177): #23     _ScaffoldLayout.performLayout (package:flutter/src/material/scaffold.dart:1003)
I/flutter (31177): #24     MultiChildLayoutDelegate._callPerformLayout (package:flutter/src/rendering/custom_layout.dart:240)
I/flutter (31177): #25     RenderCustomMultiChildLayoutBox.performLayout (package:flutter/src/rendering/custom_layout.dart:403)
I/flutter (31177): #26     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #27     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #28     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #29     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #30     _RenderCustomClip.performLayout (package:flutter/src/rendering/proxy_box.dart:1376)
I/flutter (31177): #31     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #32     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #33     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #34     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #35     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #36     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #37     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #38     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #39     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #40     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #41     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #42     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #43     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #44     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #45     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #46     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #47     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #48     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #49     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #50     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #51     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #52     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #53     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #54     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #55     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #56     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #57     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #58     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #59     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #60     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #61     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #62     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #63     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #64     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #65     RenderOffstage.performLayout (package:flutter/src/rendering/proxy_box.dart:3462)
I/flutter (31177): #66     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #67     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #68     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #69     _RenderTheatre.performLayout (package:flutter/src/widgets/overlay.dart:749)
I/flutter (31177): #70     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #71     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #72     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #73     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #74     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #75     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #76     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #77     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #78     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #79     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #80     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #81     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #82     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #83     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116)
I/flutter (31177): #84     RenderObject.layout (package:flutter/src/rendering/object.dart:1915)
I/flutter (31177): #85     RenderView.performLayout (package:flutter/src/rendering/view.dart:165)
I/flutter (31177): #86     RenderObject._layoutWithoutResize (package:flutter/src/rendering/object.dart:1757)
I/flutter (31177): #87     PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:887)
I/flutter (31177): #88     RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:504)
I/flutter (31177): #89     WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:892)
I/flutter (31177): #90     RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:370)
I/flutter (31177): #91     SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1146)
I/flutter (31177): #92     SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1083)
I/flutter (31177): #93     SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:997)
I/flutter (31177): #97     _invoke (dart:ui/hooks.dart:151)
I/flutter (31177): #98     PlatformDispatcher._drawFrame (dart:ui/platform_dispatcher.dart:308)
I/flutter (31177): #99     _drawFrame (dart:ui/hooks.dart:115)
I/flutter (31177): (elided 3 frames from dart:async)

main.dart源码:

import 'package:get/get.dart';
import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return GetMaterialApp(
      initialRoute: RouteConfig.home,
      getPages: RouteConfig.getPages,
    );
  }
}

class RouteConfig {
  static const String home = "/home";
  static final List<GetPage> getPages = [
    GetPage(
      name: home,
      page: () => const HomePage(),
      binding: HomeBinding(),
    )
  ];
}

//----------------------------------------------------home------------------------------------

class HomeBinding extends Bindings {
  @override
  void dependencies() {
    Get.lazyPut(() => HomeController());
  }
}

class HomeController extends GetxController
    with GetSingleTickerProviderStateMixin {
  final List<Tab> tabs = <Tab>[const Tab(text: 'Movie'), const Tab(text: 'Tv')];

  late TabController tabController;

  @override
  void onInit() {
    debugPrint("HomeController onInit");
    super.onInit();
    tabController = TabController(vsync: this, length: tabs.length);
    tabController.addListener(() {
      debugPrint(
          "TabController listen, index:${tabController.index}, len:${tabController.length}");
    });
  }

  @override
  void onClose() {
    debugPrint("HomeController onClose");
    tabController.dispose();
    super.onClose();
  }
}

class HomePage extends GetView<HomeController> {
  const HomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return GetBuilder<HomeController>(
      builder: (logic) {
        return Scaffold(
          appBar: AppBar(
            leading: const Icon(
              Icons.home,
            ),
            title: const Text('Home'),
            centerTitle: true,
            actions: [
              IconButton(
                icon: const Icon(Icons.search),
                color: Colors.white,
                onPressed: () {
                  debugPrint("search");
                },
              ),
            ],
            bottom: TabBar(
              isScrollable: true,
              indicatorWeight: 1,
              indicatorSize: TabBarIndicatorSize.tab,
              indicatorColor: Colors.white,
              controller: logic.tabController,
              tabs: logic.tabs,
              onTap: (index) {
                debugPrint("TabBar index: $index");
              },
            ),
          ),
          body: TabBarView(
            controller: logic.tabController,
            children: logic.tabs.map((tab) {
              debugPrint("create TabBarView, tab:${tab.text}");
              if (tab.text == null) {
                return const Center(child: Text("default"));
              }
              if (tab.text == "Movie") {
                return const StatefulMoviePage();
              }
              return Center(child: Text(tab.text!));
            }).toList(),
          ),
        );
      },
    );
  }
}

//----------------------------------------------------movie------------------------------------

class Movie {
  int id = 0;
  String name = "";
  String image = "";
  Movie(this.id, this.name, this.image);
}

class MovieState {
  late List<Movie> movies;

  MovieState() {
    movies = <Movie>[];
  }
}

class MovieController extends GetxController {
  final state = MovieState();

  @override
  void onInit() {
    debugPrint("MovieController onInit");
    super.onInit();
    state.movies = <Movie>[
      Movie(1, "movie1", "/files/1"),
      Movie(2, "movie2", "/files/1"),
      Movie(3, "movie3", "/files/1"),
    ];
  }
}

class StatefulMoviePage extends StatefulWidget {
  const StatefulMoviePage({Key? key}) : super(key: key);

  @override
  StatefulMoviePageState createState() => StatefulMoviePageState();
}

class StatefulMoviePageState extends State<StatefulMoviePage>
    with AutomaticKeepAliveClientMixin {
  @override
  Widget build(BuildContext context) {
    debugPrint("StatefulMoviePageState build start");
    super.build(context);
    return const MoviePage();
  }

  @override
  bool get wantKeepAlive => true;
}

class MoviePage extends GetView<MovieController> {
  const MoviePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    debugPrint("MoviePage build start");

    Get.put(MovieController());

    return GetBuilder<MovieController>(
      builder: (c) {
        debugPrint("movies: ${c.state.movies.length}");
        return ListView(
          children: c.state.movies.map((Movie m) {
            return ListTile(title: Text(m.name));
          }).toList(),
        );
      },
    );
  }
}

flutter

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1 个回答

得票最新

Kean

16

发布于
2022-07-22

✓ 已被采纳

出现问题
`page = _cachedPage!;
_cachedPage空安全报错的`
解决方案：
flutter sdk 中
flutter-->lib-->src-->widgets--> page_view.dart中

    double page;
    if (oldPixels == null) {
      page = _pageToUseOnStartup;
    } else if (oldViewportDimensions == 0.0) {
      // If resize from zero, we should use the _cachedPage to recover the state.
      page = _cachedPage!;
    } else {
      page = getPageFromPixels(oldPixels, oldViewportDimensions!);
    }

修改为

    double page;
    if(_cachedPage == null){
      _cachedPage = 0;
    }
    if (oldPixels == null) {
      page = _pageToUseOnStartup;
    } else if (oldViewportDimensions == 0.0) {
      // If resize from zero, we should use the _cachedPage to recover the state.
      page = _cachedPage!;
    } else {
      page = getPageFromPixels(oldPixels, oldViewportDimensions!);
    }

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