如何在警报对话框按钮上重新加载屏幕按下？

Question

我正在制作一个应用程序，该应用显示来自子reddit的图像，我想根据通过警报对话框输入的子reddit名称更改这些图像。我已经实施了如下所有内容，但是当我设置状态时，图像没有显示。如何解决这个问题？这是我的代码。

import 'package:flutter/material.dart';
import 'package:memes/screens/memes_screen.dart';

void main() {
  runApp(
    MaterialApp(
      debugShowCheckedModeBanner: false,
      home: HomePage(),
    )
  );
}

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

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {

  final TextEditingController textEditingController = TextEditingController();
  String subs = "memes";

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Color.fromARGB(255, 255, 254, 241), //Color(0xffdedede),

      appBar: AppBar(title: Text("Memes"), backgroundColor: Color(0xff008b00)),

      body: MemesScreen(subreddits: subs),

      floatingActionButton: FloatingActionButton(
        child: Icon(Icons.add),

        backgroundColor: Color(0xff008b00),

        onPressed: (){
          _showDialog();
        },
      ),
    );
  }


  void _showDialog() {
    showDialog(
      context: context,
      builder: (BuildContext context) {
        // return object of type Dialog
        return AlertDialog(

          backgroundColor: Color.fromARGB(255, 255, 254, 241),

          title: Text("Enter subreddits"),

          content: TextField(
            controller: textEditingController,
          ),
          
          actions: <Widget>[
            // usually buttons at the bottom of the dialog
            TextButton(
              child: new Text("Close", style: TextStyle(color: Color(0xff008b00))),
              onPressed: () {
                Navigator.of(context).pop();
              },
            ),

            TextButton(
              child: new Text("Get", style: TextStyle(color: Color(0xff008b00))),
              onPressed: () {
                String newSubs = textEditingController.text;
                setState(() {
                  subs = newSubs;
                });
                Navigator.of(context).pop();
              },
            ),
          ],
        );
      },
    );
  }
}

字符串subs传递给显示图像的semesscreen。如果我更改此subs在按钮上的值按_showdialog方法中的方法并设置状态，则屏幕没有重新加载。如何解决这个问题？任何帮助将不胜感激。

Answer 1

将semesscreen（subreddits：subs）包装到valuelistenablebuilder（）中。然后将字符串subs变量放入Globals.dart页面，以便可以在SetState上更改它。
编辑您的代码如下

body: ValueListenableBuilder(
      valueListenable: refreshPage,
      builder: (context, value, child) {
        return MemesScreen(subreddits: subs);
      }),
     ......

对话框页面SETSTATE将是

  setState(() {
              subs = newSubs;
              refreshPage.value == 0
                  ? refreshPage.value = 1
                  : refreshPage.value = 0;
            });

Globals

import 'package:flutter/material.dart';

String subs = 'meme';
final refreshPage = ValueNotifier<int>(0);

。
main.dart

import 'package:answer_project/globals.dart';
import 'package:answer_project/meme_screen.dart';
import 'package:flutter/material.dart';

void main() {
 runApp(const MaterialApp(
 debugShowCheckedModeBanner: false,
 home: HomePage(),
 ));
 }

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

 @override
   State<HomePage> createState() => _HomePageState();
  }

  class _HomePageState extends State<HomePage> {
  final TextEditingController textEditingController = 
  TextEditingController();
  //String subs = "memes";

 @override
  Widget build(BuildContext context) {
  return Scaffold(
    backgroundColor:
      const Color.fromARGB(255, 255, 254, 241), //Color(0xffdedede),

  appBar: AppBar(
      title: const Text("Memes"), backgroundColor: const 
  Color(0xff008b00)),

  body: ValueListenableBuilder(
      valueListenable: refreshPage,
      builder: (context, value, child) {
        return MemesScreen(subreddits: subs);
      }),

  floatingActionButton: FloatingActionButton(
    child: const Icon(Icons.add),
    backgroundColor: const Color(0xff008b00),
    onPressed: () {
      _showDialog();
    },
  ),
  );
  }

  void _showDialog() {
  showDialog(
  context: context,
  builder: (BuildContext context) {
    // return object of type Dialog
    return AlertDialog(
      backgroundColor: const Color.fromARGB(255, 255, 254, 241),
      title: const Text("Enter subreddits"),
      content: TextField(
        controller: textEditingController,
      ),
      actions: <Widget>[
        // usually buttons at the bottom of the dialog
        TextButton(
          child: const Text("Close",
              style: TextStyle(color: Color(0xff008b00))),
          onPressed: () {
            Navigator.of(context).pop();
          },
        ),

        TextButton(
          child:
              const Text("Get", style: TextStyle(color: 
         Color(0xff008b00))),
          onPressed: () {
            String newSubs = textEditingController.text;
            setState(() {
              subs = newSubs;
              refreshPage.value == 0
                  ? refreshPage.value = 1
                  : refreshPage.value = 0;
            });
            Navigator.of(context).pop();
          },
        ),
      ],
    );
  },
  );
   }
  }

meme_screen.dart

  import 'package:flutter/material.dart';

class MemesScreen extends StatelessWidget {
const MemesScreen({Key? key, required this.subreddits}) : super(key: 
key);
final String subreddits;

@override
Widget build(BuildContext context) {
return Card(
  child: Text(
    subreddits,
  ),
);
}
}

globals.dart

  import 'package:flutter/material.dart';

  String subs = 'meme';

  final refreshPage = ValueNotifier<int>(0);

另一种刷新页面的方法是：
使用navigator.pushreplacement（）代替navigator.of（context）.pop（）。

这是_showdialog（）的代码：

void _showDialog() {
showDialog(
 context: context,
 builder: (BuildContext context) {
 // return object of type Dialog
 return AlertDialog(
  backgroundColor: const Color.fromARGB(255, 255, 254, 241),
  title: const Text("Enter subreddits"),
  content: TextField(
    controller: textEditingController,
  ),
  actions: <Widget>[
    // usually buttons at the bottom of the dialog
    TextButton(
      child: const Text("Close",
          style: TextStyle(color: Color(0xff008b00))),
      onPressed: () {
        Navigator.of(context).pop();
      },
    ),

    TextButton(
      child:
          const Text("Get", style: TextStyle(color: 
     Color(0xff008b00))),
      onPressed: () {
        String newSubs = textEditingController.text;
        setState(() {
          subs = newSubs;
          refreshPage.value == 0
              ? refreshPage.value = 1
              : refreshPage.value = 0;
        });
        //Navigator.of(context).pop();
        Navigator.pushReplacement(context, MaterialPageRoute(builder: 
        (BuildContext context) => HomePage()));
      },
    ),
  ],
  );
 },
 );
  }

它将重新加载主页。但是最后一个堆栈丢失意味着您不能回到最后一页。