flutter - 编写此代码但未获得输出时出现错误

Question

import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';

class Home extends StatelessWidget {
  const Home({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: [
          const Align(
            alignment: Alignment.topRight,
            child: CircleAvatar(
              radius: 30,
              backgroundImage: AssetImage('images/image.jpeg'),
            ),
          ),
          Container(
            decoration: BoxDecoration(
                borderRadius: BorderRadius.circular(10),
                color: const Color(0xff0277bd)),
            width: 350,
            height: 120,
            child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: const [
                  Padding(
                    padding: EdgeInsets.fromLTRB(10, 30, 0, 15),
                    child: Text(
                      "New way to pay",
                      style: TextStyle(fontSize: 25, color: Colors.white),
                    ),
                  ),
                  Padding(
                    padding: EdgeInsets.only(left: 10),
                    child: Text(
                      "Try Uber Cash->",
                      style: TextStyle(fontSize: 18, color: Colors.white),
                    ),
                  ),
                ]),
          ),
          Row(
            children: [
              Padding(
                padding: const EdgeInsets.fromLTRB(20, 20, 10, 0),
                child: Container(
                    decoration: BoxDecoration(
                        borderRadius: BorderRadius.circular(10),
                        color: Colors.grey[200]),
                    width: 160,
                    height: 120,
                    child: Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      children: [
                        Padding(
                          padding: const EdgeInsets.fromLTRB(80, 0, 5, 10),
                          child: Image.asset(
                            'images/carIcon.png',
                            width: 80,
                            height: 80,
                          ),
                        ),
                        const Padding(
                          padding: EdgeInsets.only(left: 12),
                          child: Text(
                            "Ride",
                            style: TextStyle(
                              fontSize: 20,
                            ),
                          ),
                        ),
                      ],
                    )),
              ),
              Padding(
                padding: const EdgeInsets.fromLTRB(20, 20, 10, 0),
                child: Container(
                  decoration: BoxDecoration(
                      borderRadius: BorderRadius.circular(10),
                      color: Colors.grey[200]),
                  width: 160,
                  height: 120,
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Padding(
                        padding: const EdgeInsets.fromLTRB(80, 0, 5, 10),
                        child: Image.asset(
                          'images/box.png',
                          width: 80,
                          height: 80,
                        ),
                      ),
                      const Padding(
                        padding: EdgeInsets.only(left: 12),
                        child: Text(
                          "Packages",
                          style: TextStyle(
                            fontSize: 20,
                          ),
                        ),
                      ),
                    ],
                  ),
                ),
              ),
            ],
          ),
          Row(
            children: [
              Padding(
                padding: const EdgeInsets.fromLTRB(20, 15, 0, 0),
                child: ElevatedButton(
                    style: ButtonStyle(
                        backgroundColor:
                            MaterialStateProperty.all(Colors.grey[300])),
                    onPressed: () {},
                    child: const Padding(
                      padding: EdgeInsets.fromLTRB(0, 10, 0, 10),
                      child: Text(
                        "Enter pickup point",
                        style: TextStyle(fontSize: 25, color: Colors.black),
                      ),
                    )),
              ),
              ElevatedButton(
                  onPressed: () {},
                  child: const Expanded(
                    child: ListTile(
                      leading: Image(image: AssetImage('images/clock.png')),
                      title: Text("Now"),
                      trailing: Icon(Icons.arrow_drop_down),
                    ),
                  ))
            ],
          )
        ],
      ),
    );
  }
}

标签： flutterdartrender

Answer 1

违规代码是

  Row(
    children: [
      Padding(...),
      ElevatedButton(
        onPressed: () {},
        child: const Expanded(
          child: ListTile(...),
        ),
      )
    ],
  )

您不能在 ElevatedButton 内使用 Expanded 小部件，只能作为 Flex 小部件的子小部件（例如行和列）。尝试将此小部件重构为

  Row(
    children: [
      Padding(...),
      Expanded(
        child: ElevatedButton(
          onPressed: () {},
          child: ListTile(...),
        ),
      ),
    ],
  )