質問編集履歴
1
追加の質問のためのサンプルコードを追記した。
test
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test
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@@ -137,3 +137,99 @@
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とりあえずratingsとstarsを関数にしたらエラーは消えたのですが、
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上記コードでエラーが出る原因は何でしょうか?
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---
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2020/11/1/12:13追記
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サンプルコード
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```ここに言語を入力
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import 'package:flutter/material.dart';
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//import 'package:flutter/rendering.dart' show debugPaintSizeEnabled;
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void main() {
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//debugPaintSizeEnabled = true; // Remove to suppress visual layout
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//↓(1)→結果: x=10,y=10
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//runApp(MyApp._internal(x:10,y:10));
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//(2)→結果: x=20,y=0
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//runApp(MyApp.red(20));
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//(3)→結果: x=30,y=0
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runApp(MyApp(30));
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}
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class MyApp extends StatelessWidget {
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MyApp._internal({this.x, this.y}); //生成的コンストラクタ
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MyApp.red(int x) : this._internal(x: x, y: 0); //リダイレクトコンストラクタ
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factory MyApp(x) { //factoryコンストラクタ
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MyApp _ma = MyApp._internal(x: x, y: 0);
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return _ma;
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}
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final int x;
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final int y;
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@override
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Widget build(BuildContext context) {
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return MaterialApp(
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title: 'Flutter layout demo',
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home: Scaffold(
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appBar: AppBar(
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title: Text('Flutter layout demo'),
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),
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// Change to buildColumn() for the other column example
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body: Row(children: [Text("x=$x"), Text("y=$y")]),
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),
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);
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}
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}
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```
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