颤动平面按钮颜色属性不起作用

Question

在 flutter App 中，我试图为 FlatButton 设置颜色但它不起作用。找到下面的源代码。

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: SafeArea(
      child: Scaffold(
        body: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            FlatButton(
              color: Colors.red,
            ),
            FlatButton(
              color: Colors.green,
            ),
            FlatButton(
              color: Colors.blue,
            ),
          ],
        ),
      ),
    ));
  }
}

输出：

我是初学者，任何想法我的代码有什么问题？

提前致谢

Answer 1

您需要提供 child 和 onPressed 参数才能呈现小部件，否则它不会呈现，从而导致用户界面无法正常工作。

查看我修改的代码：

import 'package:flutter/material.dart';

final Color darkBlue = Color.fromARGB(255, 18, 32, 47);

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(scaffoldBackgroundColor: darkBlue),
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: Center(
          child: MyWidget(),
        ),
      ),
    );
  }
}

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: SafeArea(
      child: Scaffold(
        body: Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            FlatButton(
              color: Colors.red,
              onPressed:()=>printData(),
              child: Text("click"),
            ),
            FlatButton(
              color: Colors.green,
              onPressed:()=>printData(),
              child: Text("click"),
            ),
            FlatButton(
              color: Colors.blue,
              onPressed:()=>printData(),
              child: Text("click"),
            ),
          ],
        ),
      ),
    ));
  }
}

void printData(){
  print('Hello');
}