Flutter：“ bool”类型不是“ double”类型的子类型

时间：2020-01-27 07:45:47

标签： flutter dart

在type 'bool' is not a subtype of type 'double'内使用ListView.builder时出现错误ExpansionTile。

我可以看到扩展图块，但是当我单击扩展图块时，出现了如上所述的错误。

这是我的带有扩展图块的应用的屏幕截图-

Normal state of expansion tiles

这是扩展列表时抛出错误的屏幕截图-

Error when list is expanded

下面是我的整个代码和错误日志。

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

// Colors

var mainColor = Color(0xFF35393C);
var bgColor = Color(0xFF30313C);

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'List of Items',
      theme: new ThemeData(brightness: Brightness.dark),
      home: new Home(title: 'List of Items'),
    );
  }
}

class Home extends StatefulWidget {
  Home({Key key, this.title}) : super(key: key);

  final String title;
  @override
  _HomeState createState() => _HomeState();
}

class _HomeState extends State<Home> {
  bool success = false;

  final ScrollController _scrollController = ScrollController();

  static List<String> categories = ['Test1', 'Test1', 'Test2', 'Test3', 'Test4', 'Test5', 'Test6', 'Test7', 'Test8', 'Test9', 'Test10'];
  static List<List<String>> subCategories = [
    [
      "Approved",
      "Not Approved",
      "Under Test"
    ],
    [
      "The maximum level of brightness",
      "Screen darker",
      "Make screen the darkest"
    ],
    [
      "Mute",
      "Unmute"
    ],
    [
      "Open the roof",
      "Close the roof"
    ],
    [
      "Windows1",
      "Windows2",
      "Windows3",
      "Windows4",
      "Open windows",
      "Close windows"
    ],
    [
      "Ac1",
      "Ac2",
      "Ac3",
      "Ac4",
      "Ac5",
      "Ac6",
      "Ac7",
      "Ac8",
      "Ac9",
      "Ac10",
      "Highest fan speed",
      "Lowest fan speed"
    ],
    [
      "Open setting",
      "Help"
    ],
    [
      "Windows1",
      "Windows2",
      "Windows3",
      "Windows4",
      "Open windows",
      "Close windows"
    ],
    [
      "Ac1",
      "Ac2",
      "Ac3",
      "Ac4",
      "Ac5",
      "Ac6",
      "Ac7",
      "Ac8",
      "Ac9",
      "Ac10",
      "Highest fan speed",
      "Lowest fan speed"
    ],
    [
      "Approved",
      "Not Approved",
      "Under Test",
      "Ac1",
      "Ac2",
      "Ac3",
      "Ac4",
      "Ac5",
      "Ac6",
      "Ac7",
      "Ac8",
      "Ac9",
      "Ac10",
      "Highest fan speed",
      "Lowest fan speed",
      "Windows1",
      "Windows2",
      "Windows3",
      "Windows4",
      "Open windows",
      "Close windows"
    ],
    [
      "Windows1",
      "Windows2",
      "Windows3",
      "Windows4",
      "Open windows",
      "Close windows"
    ]
  ];
  static List<bool> activeCategories = List.filled(categories.length, false);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: bgColor,
      appBar: new AppBar(
        title: new Center(child: new Text(widget.title, textAlign: TextAlign.center)),
      ),
      body: ListView.builder(
        itemCount: categories.length,
          itemBuilder: (context, index) {
            return ExpansionTile(
              title: Text(categories.elementAt(index)),
              key: PageStorageKey<String>(categories.elementAt(index)),
              children:<Widget>[
                ListView.builder(
                  controller: _scrollController,
                  scrollDirection: Axis.horizontal,
                  shrinkWrap: true,
                  itemCount: subCategories.length,
                  itemBuilder: (context, subIndex){
                    return ListTile(
                      title: new Text(subCategories.elementAt(index).elementAt(subIndex)),
                    );
                  },
                ),
              ],
            );
          }
      ),
    );
  }
}

下面是我在执行代码时得到的日志。

I/flutter (21943): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter (21943): The following assertion was thrown building ListView(scrollDirection: horizontal,
I/flutter (21943): ScrollController#eaec6(no clients), shrinkWrap: shrink-wrapping, dependencies: [Directionality,
I/flutter (21943): MediaQuery]):
I/flutter (21943): type 'bool' is not a subtype of type 'double'
I/flutter (21943): 
I/flutter (21943): Either the assertion indicates an error in the framework itself, or we should provide substantially
I/flutter (21943): more information in this error message to help you determine and fix the underlying cause.
I/flutter (21943): In either case, please report this assertion by filing a bug on GitHub:
I/flutter (21943):   https://github.com/flutter/flutter/issues/new?template=BUG.md
I/flutter (21943): 
I/flutter (21943): The relevant error-causing widget was:
I/flutter (21943):   ListView file:///path_to_file/main.dart:198:26
I/flutter (21943): 
I/flutter (21943): When the exception was thrown, this was the stack:
I/flutter (21943): #0      ScrollPosition.restoreScrollOffset (package:flutter/src/widgets/scroll_position.dart:384:20)
I/flutter (21943): #1      new ScrollPosition (package:flutter/src/widgets/scroll_position.dart:108:7)
I/flutter (21943): #2      new ScrollPositionWithSingleContext (package:flutter/src/widgets/scroll_position_with_single_context.dart:57:8)
I/flutter (21943): #3      ScrollController.createScrollPosition (package:flutter/src/widgets/scroll_controller.dart:233:12)
I/flutter (21943): #4      ScrollableState._updatePosition (package:flutter/src/widgets/scrollable.dart:332:29)
I/flutter (21943): #5      ScrollableState.didChangeDependencies (package:flutter/src/widgets/scrollable.dart:341:5)
I/flutter (21943): #6      StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:4376:12)
I/flutter (21943): #7      ComponentElement.mount (package:flutter/src/widgets/framework.dart:4201:5)
I/flutter (21943): #8      Element.inflateWidget (package:flutter/src/widgets/framework.dart:3194:14)
I/flutter (21943): #9      Element.updateChild (package:flutter/src/widgets/framework.dart:2988:12)
I/flutter (21943): #10     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4243:16)
I/flutter (21943): #11     Element.rebuild (package:flutter/src/widgets/framework.dart:3947:5)
I/flutter (21943): #12     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:4206:5)
I/flutter (21943): #13     ComponentElement.mount (package:flutter/src/widgets/framework.dart:4201:5)
I/flutter (21943): #14     Element.inflateWidget (package:flutter/src/widgets/framework.dart:3194:14)
I/flutter (21943): #15     MultiChildRenderObjectElement.mount (package:flutter/src/widgets/framework.dart:5551:32)
I/flutter (21943): #16     Element.inflateWidget (package:flutter/src/widgets/framework.dart:3194:14)
I/flutter (21943): #17     Element.updateChild (package:flutter/src/widgets/framework.dart:2988:12)
I/flutter (21943): #18     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:5452:14)
I/flutter (21943): #19     Element.updateChild (package:flutter/src/widgets/framework.dart:2977:15)
I/flutter (21943): #20     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:5452:14)
I/flutter (21943): #21     Element.updateChild (package:flutter/src/widgets/framework.dart:2977:15)
I/flutter (21943): #22     RenderObjectElement.updateChildren (package:flutter/src/widgets/framework.dart:5161:32)
I/flutter (21943): #23     MultiChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:5561:17)
I/flutter (21943): #24     Element.updateChild (package:flutter/src/widgets/framework.dart:2977:15)
I/flutter (21943): #25     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:5452:14)
I/flutter (21943): #26     Element.updateChild (package:flutter/src/widgets/framework.dart:2977:15)
I/flutter (21943): #27     SingleChildRenderObjectElement.update (package:flutter/src/widgets/framework.dart:5452:14)
I/flutter (21943): #28     Element.updateChild (package:flutter/src/widgets/framework.dart:2977:15)
I/flutter (21943): #29     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4243:16)
I/flutter (21943): #30     Element.rebuild (package:flutter/src/widgets/framework.dart:3947:5)
I/flutter (21943): #31     StatelessElement.update (package:flutter/src/widgets/framework.dart:4298:5)
I/flutter (21943): #32     Element.updateChild (package:flutter/src/widgets/framework.dart:2977:15)
I/flutter (21943): #33     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4243:16)
I/flutter (21943): #34     Element.rebuild (package:flutter/src/widgets/framework.dart:3947:5)
I/flutter (21943): #35     StatefulElement.update (package:flutter/src/widgets/framework.dart:4413:5)
I/flutter (21943): #36     Element.updateChild (package:flutter/src/widgets/framework.dart:2977:15)
I/flutter (21943): #37     ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4243:16)
I/flutter (21943): #38     Element.rebuild (package:flutter/src/widgets/framework.dart:3947:5)
I/flutter (21943): #39     BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2432:33)
I/flutter (21943): #40     WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:773:20)
I/flutter (21943): #41     RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:283:5)
I/flutter (21943): #42     SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1102:15)
I/flutter (21943): #43     SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1041:9)
I/flutter (21943): #44     SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:957:5)
I/flutter (21943): #48     _invoke (dart:ui/hooks.dart:259:10)
I/flutter (21943): #49     _drawFrame (dart:ui/hooks.dart:217:3)
I/flutter (21943): (elided 3 frames from package dart:async)
I/flutter (21943): 
I/flutter (21943): ════════════════════════════════════════════════════════════════════════════════════════════════════

2 个答案:

答案 0 :(得分：1)

试试看:) 

class _HomeState extends State<Home> {
      bool success = false;

      final ScrollController _scrollController = ScrollController();

      static List<String> categories = ['Test1', 'Test1', 'Test2', 'Test3', 'Test4', 'Test5', 'Test6', 'Test7', 'Test8', 'Test9', 'Test10'];
      static List<List<String>> subCategories = [
        [
          "Approved",
          "Not Approved",
          "Under Test"
        ],
        [
          "The maximum level of brightness",
          "Screen darker",
          "Make screen the darkest"
        ],
        [
          "Mute",
          "Unmute"
        ],
        [
          "Open the roof",
          "Close the roof"
        ],
        [
          "Windows1",
          "Windows2",
          "Windows3",
          "Windows4",
          "Open windows",
          "Close windows"
        ],
        [
          "Ac1",
          "Ac2",
          "Ac3",
          "Ac4",
          "Ac5",
          "Ac6",
          "Ac7",
          "Ac8",
          "Ac9",
          "Ac10",
          "Highest fan speed",
          "Lowest fan speed"
        ],
        [
          "Open setting",
          "Help"
        ],
        [
          "Windows1",
          "Windows2",
          "Windows3",
          "Windows4",
          "Open windows",
          "Close windows"
        ],
        [
          "Ac1",
          "Ac2",
          "Ac3",
          "Ac4",
          "Ac5",
          "Ac6",
          "Ac7",
          "Ac8",
          "Ac9",
          "Ac10",
          "Highest fan speed",
          "Lowest fan speed"
        ],
        [
          "Approved",
          "Not Approved",
          "Under Test",
          "Ac1",
          "Ac2",
          "Ac3",
          "Ac4",
          "Ac5",
          "Ac6",
          "Ac7",
          "Ac8",
          "Ac9",
          "Ac10",
          "Highest fan speed",
          "Lowest fan speed",
          "Windows1",
          "Windows2",
          "Windows3",
          "Windows4",
          "Open windows",
          "Close windows"
        ],
        [
          "Windows1",
          "Windows2",
          "Windows3",
          "Windows4",
          "Open windows",
          "Close windows"
        ]
      ];
      static List<bool> activeCategories = List.filled(categories.length, false);

      @override
      Widget build(BuildContext context) {
        return Scaffold(
          backgroundColor: bgColor,
          appBar: new AppBar(
            title: new Center(child: new Text(widget.title, textAlign: TextAlign.center)),
          ),
          body: ListView.builder(
              itemCount: categories.length,
              itemBuilder: (context, index) {
                return ExpansionTile(
                  title: Text(categories.elementAt(index)),
                  key: PageStorageKey<String>(categories.elementAt(index)),
                  children: subCategories[index].map((text){
                    return ListTile(title: Text(text),);
                  }).toList(),
                );
              }
          ),
        );
      }
    }

我希望这对您有帮助...

答案 1 :(得分：0)

为我工作：

...键： PageStorageKey ...

来源： https://github.com/flutter/flutter/issues/36539#issuecomment-561848176

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