1

我在一个有状态的小部件中有一个变量，其中包含一个字符串值。我从另一个飞镖文件中调用了一个小部件。我需要从此小部件更改有状态小部件中变量的值。我尝试了 valuelistanablebuilder但它只在该 dart 文件中调用函数时才听值。请告诉我如何做到这一点的方法和示例代码。

import 'package:flutter/material.dart';
import 'package:messaging_service/components/app_bar.dart';
import 'package:messaging_service/components/home_pages/all_messages.dart';
import 'package:messaging_service/components/home_pages/stories.dart';
import 'package:messaging_service/components/search_bar.dart';
import 'package:messaging_service/components/strings.dart';
import 'package:messaging_service/components/style.dart';

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

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

class _HomeMobileState extends State<HomeMobile> {
  var currentPage = 'all';
  TextEditingController searchChatController = TextEditingController();
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: lightColor,
      appBar: AppBarHomeMobile(context),
      body: SingleChildScrollView(
        child: Column(
          children: [
            AppBarHomeExtend(),
            const SizedBox(
              height: 10,
            ),
            //To Call a Widget
          ],
        ),
      ),
    );
  }
}

在这个AppBarHomeExtend()有一些按钮..

Widget AppBarHomeExtend() {
  return Container(
    height: 80,
    decoration: BoxDecoration(
        color: lightColor,
        boxShadow: [
          BoxShadow(color: darkColor, blurRadius: 5),
        ],
        borderRadius: const BorderRadius.only(
            bottomLeft: Radius.circular(35), bottomRight: Radius.circular(35))),
    child: Row(
      mainAxisAlignment: MainAxisAlignment.spaceAround,
      children: [
        HRButtons('All Messages', () {}),
        HRButtons('Groups', () {  }),
        HRButtons('Stories', () {}),
        HRButtons('Calls', () {}),
      ],
    ),
  );
}

当调用这些按钮时，我需要从那个有状态的小部件中更改变量 currentPage 的值。

4

2 回答 2

1

首先，把你AppBarHomeExtend变成一个适当的小部件，它以回调函数作为参数：

import 'package:flutter/material.dart';

class ExtendedAppBar extends StatelessWidget {
  final void Function(String) setPage;

  const ExtendedAppBar({Key? key, required this.setPage}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      height: 80,
      decoration: BoxDecoration(
          color: Colors.blue.shade50,
          boxShadow: [
            BoxShadow(color: Colors.blue.shade900, blurRadius: 5),
          ],
          borderRadius: const BorderRadius.only(bottomLeft: Radius.circular(35), bottomRight: Radius.circular(35))),
      child: Row(
        mainAxisAlignment: MainAxisAlignment.spaceAround,
        children: [
          HRButtons('All Messages', () => setPage('All Messages')),
          HRButtons('Groups', () => setPage('Groups')),
          HRButtons('Stories', () => setPage('Stories')),
          HRButtons('Calls', () => setPage('Calls')),
        ],
      ),
    );
  }
}

然后在你的_HomeMobileState课堂上，使用这个：

ExtendedAppBar(
  setPage: (String value) {
    setState(() {
      currentPage = value;
    });
  },
),
于 2021-11-15T03:01:45.857 回答
0

您最好需要使用状态管理来获得更好的解决方案。检查这个包

 floatingActionButton: FloatingActionButton(
    key: const Key('increment_floatingActionButton'),

    /// Calls `context.read` instead of `context.watch` so that it does not rebuild
    /// when [Counter] changes.
    onPressed: () => context.read<Counter>().increment(),
    tooltip: 'Increment',
    child: const Icon(Icons.add),
  ),

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

  @override
  Widget build(BuildContext context) {
     return Text(

    /// Calls `context.watch` to make [Count] rebuild when [Counter]      changes.
       '${context.watch<Counter>().count}',
        key: const Key('counterState'),
        style: Theme.of(context).textTheme.headline4);
  }
}
于 2021-11-14T15:26:43.950 回答