Q&A
おそらく何かしらのWidgetのサイズ（制約）が決められていない為、エラーになっているように思われます。
問題を再現する為の最小限のソースコードも記載してもらえれば、具体的な回答が出来ます。
その際は、マークダウン記法でソースコードを記載してください。（```で囲む）
```
ソースコード
```
Flutterで簡単なアプリを実行しようとすると（ラジオボタンとTextとTextFieldの組み合わせ）
以下のようのlお具をはきアプリが描画されず、シミュレータに真っ白な画面が表示されます。（AppBarのところだけはちゃんと表示されています）以下のような大量のログが出ていました。このエラーが何を指しているのか、及びその際の解決策を押していただけると幸いです。
Xcode build done. 23.1s
flutter: ══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞═════════════════════════════════════════════════════════
flutter: The following assertion was thrown during performLayout():
flutter: An InputDecorator, which is typically created by a TextField, cannot have an unbounded width.
flutter: This happens when the parent widget does not provide a finite width constraint. For example, if the
flutter: InputDecorator is contained by a Row, then its width must be constrained. An Expanded widget or a
flutter: SizedBox can be used to constrain the width of the InputDecorator or the TextField that contains it.
flutter: 'package:flutter/src/material/input_decorator.dart':
flutter: Failed assertion: line 945 pos 7: 'layoutConstraints.maxWidth < double.infinity'
flutter:
flutter: Either the assertion indicates an error in the framework itself, or we should provide substantially
flutter: more information in this error message to help you determine and fix the underlying cause.
flutter: In either case, please report this assertion by filing a bug on GitHub:
flutter: https://github.com/flutter/flutter/issues/new?template=BUG.md
flutter:
flutter: The relevant error-causing widget was:
flutter: TextFormField file:///Users/aoxitaidi/AndroidStudioProjects/flutter_okyaku/lib/main.dart:73:21
flutter:
flutter: When the exception was thrown, this was the stack:
flutter: #2 _RenderDecoration._layout (package:flutter/src/material/input_decorator.dart:945:7)
flutter: #3 _RenderDecoration.performLayout (package:flutter/src/material/input_decorator.dart:1262:44)
flutter: #4 RenderObject.layout (package:flutter/src/rendering/object.dart:1767:7)
flutter: #5 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:111:13)
flutter: #6 RenderObject.layout (package:flutter/src/rendering/object.dart:1767:7)
flutter: #7 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:111:13)
flutter: #8 RenderObject.layout (package:flutter/src/rendering/object.dart:1767:7)
flutter: #9 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:111:13)
flutter: #10 RenderObject.layout (package:flutter/src/rendering/object.dart:1767:7)
flutter: #11 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:111:13)
flutter: #12 RenderObject.layout (package:flutter/src/rendering/object.dart:1767:7)
以下省略
```
import 'package:flutter/material.dart';
import 'package:flutter/cupertino.dart';
void main() => runApp((new MyApp()));
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'okyaku',
home: MyHomePage(
),
);
}
}
class MyHomePage extends StatefulWidget {
@override
_MyHomePageState createState() => _MyHomePageState();
}
enum gender { male, female }
class _MyHomePageState extends State<MyHomePage> {
gender _character = gender.male;
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('お客様入力情報'),
),
body: Column(
children: <Widget>[
Row(
children: <Widget>[
Text('性別'),
Radio(
value: gender.male,
groupValue: _character,
onChanged: (gender value) {
setState(() {
_character = value;
});
},
),
Text('男性'),
//Text('女性'),
Radio(
value: gender.female,
groupValue: _character,
onChanged: (gender value) {
setState(() {
_character = value;
});
},
),
Text('女性')
],
),
Row(
children: <Widget>[
Text('名前'),
TextFormField(
decoration: InputDecoration(
hintText: 'お名前を入力してください'
),
)
],
),
Row(
children: <Widget>[
Text('年齢'),
],
),
Row(
children: <Widget>[
Text('メモ'),
TextFormField(
decoration: InputDecoration(
hintText: 'ご自由にご記入ください'
),
)
],
)
],
),
);
}
}
```
回答1件
0
ベストアンサー
TextFormFieldの制約がないためにエラーになっているようです。
Expandedで最大の大きさにしたり、Containerでサイズを指定すると解決できます。
import 'package:flutter/material.dart'; import 'package:flutter/cupertino.dart'; void main() => runApp((new MyApp())); class MyApp extends StatelessWidget { @override Widget build(BuildContext context) { return MaterialApp( title: 'okyaku', home: MyHomePage(), ); } } class MyHomePage extends StatefulWidget { @override _MyHomePageState createState() => _MyHomePageState(); } enum gender { male, female } class _MyHomePageState extends State<MyHomePage> { gender _character = gender.male; @override Widget build(BuildContext context) { return Scaffold( appBar: AppBar( title: Text('お客様入力情報'), ), body: Column( children: <Widget>[ Row( children: <Widget>[ Text('性別'), Radio( value: gender.male, groupValue: _character, onChanged: (gender value) { setState(() { _character = value; }); }, ), Text('男性'), //Text('女性'), Radio( value: gender.female, groupValue: _character, onChanged: (gender value) { setState(() { _character = value; }); }, ), Text('女性') ], ), Row( children: <Widget>[ Text('名前'), Expanded( // ****** 例: Expanded 追加 ***** child: TextFormField( decoration: InputDecoration(hintText: 'お名前を入力してください'), ), ) ], ), Row( children: <Widget>[ Text('年齢'), ], ), Row( children: <Widget>[ Text('メモ'), Container( // ****** 例: Container 追加 ***** width: 200, child: TextFormField( decoration: InputDecoration(hintText: 'ご自由にご記入ください'), ), ) ], ) ], ), ); } }
[補足]
コメント欄はマークダウン記法が使えないらしいので、追記は質問文にしてもらえると読みやすいです。
※質問文は編集できます。
投稿2020/07/05 07:28
総合スコア1186
ご回答いただきありがとうございます！
なるほど、TextFormFIeldにはサイズを定めてあげないといけないのですね。
このような素人質問にわざわざ時間を割いて、ご協力いただきありがとうございました！とても感謝しています！
この先も色々と質問に答えていただけるとありがたいです。
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