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| import 'package:flutter/material.dart'; | |
| void main() { | |
| // 1. 必要最小限で実行 | |
| runApp( | |
| MaterialApp( | |
| home: Scaffold( | |
| backgroundColor: Colors.black, | |
| body: RichText( | |
| text: const TextSpan(text: 'Hello World'), | |
| ), | |
| ), | |
| ), | |
| ); | |
| // 2. コメントアウトを外し, Appを2回走らせる | |
| runApp( | |
| MaterialApp( | |
| home: Scaffold( | |
| backgroundColor: Colors.black, | |
| body: RichText( | |
| text: const TextSpan(text: 'Hello Shanghai'), | |
| ), | |
| ), | |
| ), | |
| ); | |
| } |
Author
Author
エラー
Launching lib/main.dart on sdk gphone64 x86 64 in debug mode...
✓ Built build/app/outputs/flutter-apk/app-debug.apk.
Connecting to VM Service at ws://127.0.0.1:63050/rOMmVk0U_Kk=/ws
════════ Exception caught by widgets library ═══════════════════════════════════
The following assertion was thrown attaching to the render tree:
No Directionality widget found.
RichText widgets require a Directionality widget ancestor.
The specific widget that could not find a Directionality ancestor was: RichText
softWrap: wrapping at box width
maxLines: unlimited
text: "Hello World"
dirty
The ownership chain for the affected widget is: "RichText ← [root]"
Typically, the Directionality widget is introduced by the MaterialApp or WidgetsApp widget at the top of your application widget tree. It determines the ambient reading direction and is used, for example, to determine how to lay out text, how to interpret "start" and "end" values, and to resolve EdgeInsetsDirectional, AlignmentDirectional, and other *Directional objects.
When the exception was thrown, this was the stack
#0 debugCheckHasDirectionality.<anonymous closure>
#1 debugCheckHasDirectionality
#2 RichText.createRenderObject
#3 RenderObjectElement.mount
#4 MultiChildRenderObjectElement.mount
#5 Element.inflateWidget
#6 Element.updateChild
#7 RenderObjectToWidgetElement._rebuild
#8 RenderObjectToWidgetElement.mount
#9 RenderObjectToWidgetAdapter.attachToRenderTree.<anonymous closure>
#10 BuildOwner.buildScope
#11 RenderObjectToWidgetAdapter.attachToRenderTree
#12 WidgetsBinding.attachRootWidget
#13 WidgetsBinding.scheduleAttachRootWidget.<anonymous closure>
#17 _RawReceivePort._handleMessage (dart:isolate-patch/isolate_patch.dart:192:26)
(elided 3 frames from class _Timer and dart:async-patch)
════════════════════════════════════════════════════════════════════════════════
E/SurfaceSyncer( 5049): Failed to find sync for id=0
W/Parcel ( 5049): Expecting binder but got null!
Author
エラーは MaterialApp ないから発生していたので追加
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flutter プロジェクトを作成し, main にこれを貼ると確認できる.
https://www.youtube.com/watch?v=996ZgFRENMs&ab_channel=Flutter に出てきたコードです.