Status widget daftar tidak diperbarui dengan StatefulBuilder di flutter

Question

Pertanyaan saya adalah setstate tidak berfungsi dengan statefulbuilder dan daftar widget saya ingin memperbarui warna penampung. Meskipun warna tombol sedang diperbarui. Saya tidak yakin apa masalahnya

 Color currentColor = Colors.grey;
 void changecolor(Color color) {
   setState(() {
   currentColor = color;
   });
 }
 List<Widget> list = [];
 @override
Widget build(BuildContext context) {
   return Container(
   child: Stack(
       children: [
         Container(
          height: MediaQuery.of(context).size.height,
           width: MediaQuery.of(context).size.width,
       ),
         Positioned(
            right: 50,
          top: 50,
          child: RaisedButton(
            elevation: 3.0,
             onPressed: () {
              showDialog(
                context: context,
                 builder: (BuildContext context) {
                   return AlertDialog(
                     titlePadding: const EdgeInsets.all(0.0),
                    contentPadding: const EdgeInsets.all           (0.0),
                      content: SingleChildScrollView(
                       child: MaterialPicker(
                        pickerColor: currentColor,
                        onColorChanged: changecolor,
                        enableLabel: true,
                      ),
                   ),
                  );
              },
             );
          },
          child: const Text('Change me'),
          color: currentColor,
          
        ),
      ),
      ...list,
      Positioned(
        left: 50,
        top: 50,
        child: RaisedButton(
          child: Text(
            'Add another Color Sticker',
            style: TextStyle(fontSize: 10),
            ),
            onPressed: () {
               setState(
                () {
                 list.add(
                  StatefulBuilder(
                      builder: (BuildContext context,                     StateSetter setState) {
                         return Positioned(
                           left: 100,
                            top: 100,
                           child: Container(
                             color: currentColor,
                              height: 100,
                             width: 100,
                           ),
                          );
                       },
                     ),
                   );
                 },
               );
             },
            ),
          ),
       ],
      ),
    );

Adakah yang bisa membantu saya dengan masalah ini.Saya tidak dapat memahami mengapa tidak memperbarui warna wadah Terima kasih sebelumnya.

Answer 1

Anda dapat menyalin dan menempel menjalankan kode lengkap di bawah
ini. Dalam hal ini, Anda dapat menggunakan ValueNotifier<Color>dan ValueListenableBuilder
potongan kode

ValueNotifier<Color> currentColor = ValueNotifier(Colors.grey);
...
MaterialPicker(
    pickerColor: currentColor.value,
...
child: const Text('Change me'),
              color: currentColor.value,
...
list.add(ValueListenableBuilder(
                        valueListenable: currentColor,
                        builder: (BuildContext context, Color current,
                            Widget child) {
                          return Positioned(
                            left: 100,
                            top: 100,
                            child: Container(
                              color: current,
                              height: 100,
                              width: 100,
                            ),
                          );
                        }));    

demo kerja

kode lengkap

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

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Test(),
    );
  }
}

class Test extends StatefulWidget {
  @override
  _TestState createState() => _TestState();
}

class _TestState extends State<Test> {
  ValueNotifier<Color> currentColor = ValueNotifier(Colors.grey);

  void changecolor(Color color) {
    setState(() {
      currentColor.value = color;
    });
  }

  List<Widget> list = [];

  @override
  Widget build(BuildContext context) {
    return Container(
      child: Stack(
        children: [
          Container(
            height: MediaQuery.of(context).size.height,
            width: MediaQuery.of(context).size.width,
          ),
          Positioned(
            right: 50,
            top: 50,
            child: RaisedButton(
              elevation: 3.0,
              onPressed: () {
                showDialog(
                  context: context,
                  builder: (BuildContext context) {
                    return AlertDialog(
                      titlePadding: const EdgeInsets.all(0.0),
                      contentPadding: const EdgeInsets.all(0.0),
                      content: SingleChildScrollView(
                        child: MaterialPicker(
                          pickerColor: currentColor.value,
                          onColorChanged: changecolor,
                          enableLabel: true,
                        ),
                      ),
                    );
                  },
                );
              },
              child: const Text('Change me'),
              color: currentColor.value,
            ),
          ),
          ...list,
          Positioned(
            left: 50,
            top: 50,
            child: RaisedButton(
              child: Text(
                'Add another Color Sticker',
                style: TextStyle(fontSize: 10),
              ),
              onPressed: () {
                setState(
                  () {
                    list.add(ValueListenableBuilder(
                        valueListenable: currentColor,
                        builder: (BuildContext context, Color current,
                            Widget child) {
                          return Positioned(
                            left: 100,
                            top: 100,
                            child: Container(
                              color: current,
                              height: 100,
                              width: 100,
                            ),
                          );
                        }));
                  },
                );
              },
            ),
          ),
        ],
      ),
    );
  }
}