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android - 未为类型“Type”定义运算符“[]”。Flutter ListView 构建器

问题描述

我正在制作水平ListView.builder的“卡片”，但在itemBuilder选项中，在 item 参数中，我输入buildCard(item: int [index])了但它向我显示了错误：

未为类型“Type”定义运算符“[]”。尝试定义运算符'[]'。

我想解决这个错误。

我的代码：

import 'package:flutter/material.dart';

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  _HomePageState createState() => _HomePageState();
}

class CardItem {
  final String assetImage;
  final String title;

  const CardItem({
    required this.assetImage,
    required this.title,
  });
}

class _HomePageState extends State<HomePage> {
  List<CardItem> items = [
    CardItem(title: 'Card1', assetImage: 'images/movie/01.webp'),
    CardItem(title: 'Card2', assetImage: 'images/movie/02.png'),
    CardItem(title: 'Card3', assetImage: 'images/movie/03.png'),
  ];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        body: Container(
            margin: const EdgeInsets.symmetric(vertical: 20.0),
            height: 250,
            child: ListView.separated(
                itemBuilder: (context, index) => buildCard(item: int[index]),
                separatorBuilder: (context, _) => SizedBox(width: 12),
                itemCount: 3)));
  }

  Widget buildCard({
    required CardItem item,
  }) =>
      Container(
          width: 170,
          color: Colors.red,
          child: Column(
            children: [
              Expanded(
                child: Image(
                  image: AssetImage(item.assetImage),
                  fit: BoxFit.cover,
                ),
              )
            ],
          ));
}

标签： androidflutterdart

解决方案

您需要在 buildCard(item: items[index]) 中使用项目列表而不是 int

class _HomePageState extends State<HomePage> {
  List<CardItem> items = [
    CardItem(title: 'Card1', assetImage: 'images/movie/01.webp'),
    CardItem(title: 'Card2', assetImage: 'images/movie/02.png'),
    CardItem(title: 'Card3', assetImage: 'images/movie/03.png'),
  ];

  @override
Widget build(BuildContext context) {
  return Scaffold(
      body: Container(
          margin: const EdgeInsets.symmetric(vertical: 20.0),
          child: ListView.separated(
              itemBuilder: (context, index) => buildCard(item: items[index]),
              separatorBuilder: (context, _) => SizedBox(height: 12),
              itemCount: 3)));
}

Widget buildCard({
  required CardItem item,
}) =>
    Container(
        width: 170,
        height: 250,
        color: Colors.red,
        child: Column(
          children: [
            Expanded(
              child: Image.network('https://github.com/flutter/plugins/raw/master/packages/video_player/video_player/doc/demo_ipod.gif?raw=true') 
,
            )
          ],
        ));
}

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