Question

您好，我想将信息从其所在的构造函数传递到小部件中。

但是它返回错误：

“只能在初始化程序中访问静态成员”。

此行返回错误：

Upload(currentUsers: widget.currentUsers,),

请帮助我

这是我的代码。

import 'package:curved_navigation_bar/curved_navigation_bar.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:junk_stores/Curved4/Notifications.dart';
import 'package:junk_stores/Curved4/Payments.dart';
import 'package:junk_stores/Curved4/profilePage.dart';
import 'dart:ui' as ui;
import 'package:junk_stores/Curved4/homeScreen.dart';
import 'package:junk_stores/Curved4/uploadPage.dart';
import 'package:font_awesome_flutter/font_awesome_flutter.dart';
import 'package:junk_stores/models/user.dart';
import 'package:junk_stores/pages/home.dart';
import 'package:junk_stores/pages/search.dart';
import 'package:junk_stores/pages/upload.dart';



class BottomNavbar extends StatefulWidget {
 final User currentUsers;
  BottomNavbar({@required this.currentUsers}){
    print(currentUsers);
  }
  @override
  _BottomNavbarState createState() => _BottomNavbarState();
}



class _BottomNavbarState extends State<BottomNavbar> {
  int _currentIndex = 0;

  final List<Widget> _children = [
      HomeS(),
      Search(),
      Upload(currentUsers: widget.currentUsers,), // the error is here
      Notifications(),//trending and notifications page
      Profile(),
     ];

  void onTappedBar (int index) {
         setState(() {
            _currentIndex = index;
         });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: _children[_currentIndex],
      bottomNavigationBar: CurvedNavigationBar(
        color: Colors.white,
        onTap : onTappedBar,
        buttonBackgroundColor: Colors.white,
        backgroundColor: Colors.purple[400],
        animationCurve: Curves.ease,
        animationDuration: Duration(milliseconds: 700),
        index: 0,
        height: MediaQuery.of(context).size.height * 0.07407407,//52 pixels
        items: <Widget>[

           ShaderMask(
            blendMode: BlendMode.srcIn,
            shaderCallback: (Rect bounds) {
              return ui.Gradient.linear(
                Offset(4.0, 24.0),
                Offset(24.0, 4.0),
                [
                Colors.red[600],
                Colors.purple,
                ],
              );
            },
            child: Icon(
              FontAwesomeIcons.home,
              size: 24,

                 ),
           ),
           ShaderMask(
            blendMode: BlendMode.srcIn,
            shaderCallback: (Rect bounds) {
              return ui.Gradient.linear(
                Offset(4.0, 24.0),
                Offset(24.0, 4.0),
                [
                Colors.red[600],
                Colors.purple,
               ],
              );
            },
            child: Icon(
               FontAwesomeIcons.search,
              size: 24,
                 ),
          ),
          ShaderMask(
            blendMode: BlendMode.srcIn,
            shaderCallback: (Rect bounds) {
              return ui.Gradient.linear(
                Offset(4.0, 24.0),
                Offset(24.0, 4.0),
                [
                 Colors.red[600],
                Colors.purple,
               ],
              );
            },
            child: Icon(
              FontAwesomeIcons.plus,
              size: 24,
                 ),

         ),

         ShaderMask(
            blendMode: BlendMode.srcIn,
            shaderCallback: (Rect bounds) {
              return ui.Gradient.linear(
                Offset(4.0, 24.0),
                Offset(24.0, 4.0),
                [
                Colors.red[600],
                Colors.purple,
               ],
              );
            },
            child: Icon(
              Icons.trending_up,
              size: 29,
                 ),

         ),

         ShaderMask(
            blendMode: BlendMode.srcIn,
            shaderCallback: (Rect bounds) {
              return ui.Gradient.linear(
                Offset(4.0, 24.0),
                Offset(24.0, 4.0),
                [
               Colors.red[600],
                Colors.purple,
               ],
              );
            },
            child: Icon(
              FontAwesomeIcons.user,
              size: 24,
                 )

         )
        ],

      ),
    );
  }
}

我曾尝试阅读其他解决方案，但我似乎并没有理解。我只想将构造函数中的信息传递给Upload Widget。 ................................................... ...................

这是我的上载代码的顶部。

class Upload extends StatefulWidget {
  final User currentUsers;
  Upload({@required this.currentUsers}){
    print(currentUsers);
  }
@override
  _UploadState createState() => _UploadState();
}
class _UploadState extends State<Upload> {


 buildSplashSreen(){
   return Scaffold(
     appBar: AppBar(

Answer 1

在初始化状态之前，您无法访问“ widget”（widget.currentUsers）。

类似的东西：

class _BottomNavbarState extends State<BottomNavbar> {
  int _currentIndex = 0;

  List<Widget> _children;

  @override
  initState() {
   _children = [
      HomeS(),
      Search(),
      Upload(currentUsers: widget.currentUsers,),
      Notifications(),
      Profile(),
     ]
  }

 ...
}

或作为吸气剂

List<Widget> get _children => [
      HomeS(),
      Search(),
      Upload(currentUsers: widget.currentUsers,),
      Notifications(),
      Profile(),
     ];

Answer 2

尝试这样：

MyWidget(currentUsers: someuser);

class MyWidget extends StatefulWidget {
  final User currentUsers;
  const MyWidget({Key key, this.currentUsers}) : super(key: key);

  @override
  _MyWidgetState createState() => _MyWidgetState(this.currentUsers);
}

class _MyWidgetState extends State<MyWidget> {
  final User currentUsers;
  _MyWidgetState(this.currentUsers);

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

    );
  }
}

在初始化错误中只能访问静态成员

2 个答案: