Flutter RenderBox 未布局 SingleChildScrollView

Question

我的代码：

var _body = Builder(builder: (BuildContext context) {
return Padding(
  padding: EdgeInsets.only(
      top: 340),
  child: Column(
    children: [
      SizedBox(height: 10),
      _customWidget,
      SizedBox(height: 10),
      Expanded(
        child: SingleChildScrollView(
            scrollDirection: Axis.vertical,
            child: Column(
              mainAxisSize: MainAxisSize.max,
              mainAxisAlignment: MainAxisAlignment.start,
              children: <Widget>[
                CustomWidget(
                  txt: 'item1',
                  txt2: 'info',
                  callback: () {
                    _showDialog(context);
                  },
                ),
                CustomWidget(
                  txt: 'item1',
                  txt2: 'info',
                  callback: () {
                    _showDialog(context);
                  },
                  },
                ),
                CustomWidget(
                  txt: 'item1',
                  txt2: 'info',
                  callback: () {
                    _showDialog(context);
                  },
                ),
                _customWidget,
                _customWidget,
              ],
            )),
      )
    ],
  ),
);

抛出了另一个异常：RenderFlex 子级具有非零 Flex，但传入的宽度约束是无界的。 抛出另一个异常：RenderBox 未布局：RenderFlex#97324 relayoutBoundary=up40 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE

我尝试过将孩子包裹成展开的，但这不起作用。 我无法向滚动视图添加任何高度，因为滚动视图内的子项仅在条件正确时才会显示。因此列表的高度取决于将显示多少个子项。

Answer 1

我想你想做一个高度有限的

SingleChildScrollView

。

您可以用

Container

或

SizedBox

包裹它并指定您想要的高度。

例如这样：

import 'package:flutter/material.dart';

void main() {
  runApp(const TstApp());
}

class TstApp extends StatelessWidget {
  const TstApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Tst',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: HomePage(),
    );
  }
}

class HomePage extends StatelessWidget {
  HomePage({super.key});
  final Widget _customWidget = CustomWidget(
    txt: 'txt',
    txt2: 'txt2',
    callBack: () {},
  );
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Padding(
        padding: const EdgeInsets.only(top: 10), // was: 340
        child: Column(
          children: [
            const SizedBox(height: 10),
            _customWidget,
            const SizedBox(height: 10),
            SizedBox(
              height: 300,
              child: SingleChildScrollView(
                scrollDirection: Axis.vertical,
                child: Column(
                  mainAxisSize: MainAxisSize.max,
                  mainAxisAlignment: MainAxisAlignment.start,
                  children: [
                    CustomWidget(
                      txt: 'item1',
                      txt2: 'info',
                      callBack: () {
                        _showDialog(context);
                      },
                    ),
                    CustomWidget(
                      txt: 'item2',
                      txt2: 'info',
                      callBack: () {
                        _showDialog(context);
                      },
                    ),
                    CustomWidget(
                      txt: 'item3',
                      txt2: 'info',
                      callBack: () {
                        _showDialog(context);
                      },
                    ),
                    _customWidget,
                    _customWidget,
                  ],
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }

  void _showDialog(BuildContext context) {
    showDialog(
      context: context,
      builder: (BuildContext context) {
        return AlertDialog(
          title: const Text('Alert'),
          content: const Text('This is a simple alert dialog.'),
          actions: <Widget>[
            TextButton(
              onPressed: () {
                Navigator.of(context).pop();
              },
              child: const Text('OK'),
            ),
          ],
        );
      },
    );
  }
}

class CustomWidget extends StatelessWidget {
  const CustomWidget({
    super.key,
    required this.txt,
    required this.txt2,
    this.callBack,
  });
  final String txt;
  final String txt2;
  final VoidCallback? callBack;
  @override
  Widget build(BuildContext context) {
    return ListTile(
      title: Text(txt),
      subtitle: Text(txt2),
      onTap: callBack,
    );
  }
}