错误：无法使用静态访问权限访问实例成员'imageUrl'。 （位于[store] lib \ main.dart：82处的static_access_to_instance_member）

Question

我是Flutter的新手，我正在尝试为一种在线商店创建一个gridview。 JSON文件已上传到服务器，然后我通过其属性（如JSON Keys）创建了一个类。当我想实例化这些属性以使其喜欢image或text时，它显示此错误： 错误：无法使用静态访问权限访问实例成员'imageUrl'。 （位于[store] lib \ main.dart：82处的static_access_to_instance_member）

这是我的代码：

import 'dart:convert';
import 'package:flutter/material.dart';
import 'BottomNVG.dart';
import 'package:http/http.dart';
import 'product.dart';
void main() => runApp(MaterialApp(
  debugShowCheckedModeBanner: false,
  home:store()
));
class store extends StatefulWidget {
  @override
  _storeState createState() => _storeState();
}

class _storeState extends State<store> {
  List<product> _items = [];
  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    fetchItems();
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.grey[200],
      appBar: AppBar(
        title:Center(child: Text('Store')),
        backgroundColor: Colors.red,
        leading: Icon(Icons.arrow_back),
        actions: <Widget>[
          Icon(Icons.search),
        ],
    ),
    body: Padding(
        padding: EdgeInsets.all(8.0),
        child: GridView.count(
          crossAxisCount: 2,

          crossAxisSpacing: 3,
          mainAxisSpacing: 3,

          children:
            List.generate(_items.length,(int position){
                return genearateItem();
            }),
        ),
      ),
        bottomNavigationBar:BottomNVG(),
        floatingActionButton: FloatingActionButton(
          child:Icon(Icons.add),
          backgroundColor: Colors.red[900],
          onPressed: (){},
        ),
        floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
    );
  }
  void fetchItems() async{
    var url = 'http://artamweb.ir/test/test.json';
    Response response = await get(url);
    setState(() {
       var productJson = json.decode(utf8.decode(response.bodyBytes));
       for (var i in productJson){
         var productItem = product(i['prodct_name'],i['id'],i['price'],i['image_url'],i['off'],i['description']);
         _items.add(productItem);
       }
    });
  }
  Card genearateItem(){
    return Card(
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.all(Radius.circular(20)),
      ),
      elevation: 3,
      child: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Container(
              width:90,
              height:90,
              child:Image.network(product.imageUrl),
            ),
            Text(product.productName,
              style: TextStyle(
                fontFamily:'Vazir',
                color:Colors.red[900],
                fontSize:14.0,
              ),
            ),
            Text(product.price,
              style: TextStyle(
                fontFamily:'Vazir',
                color:Color(0xFF575E67),
                fontSize:14.0,
              ),
            ),
          ],
        ),
      ),
    );
  }
}

] 2

product.dart
class product{
  String _productName;
  int _id;
  String _price;
  String _imageUrl;
  String _off;
  String _description;

  product(this._productName, this._id, this._price, this._imageUrl, this._off,
      this._description);

  String get description => _description;

  String get off => _off;

  String get imageUrl => _imageUrl;

  String get price => _price;

  int get id => _id;

  String get productName => _productName;
}

Answer 1

您需要创建一个类的实例，另外最好使用大写字母作为类名：

class Product{
  String _productName;
  int _id;
  String _price;
  String _imageUrl;
  String _off;
  String _description;

  Product();

  Product.createProduct(this._productName, this._id, this._price, this._imageUrl, this._off,
      this._description);

  String get description => _description;

  String get off => _off;

  String get imageUrl => _imageUrl;

  String get price => _price;

  int get id => _id;

  String get productName => _productName;
}

然后做：

  var poduct = Product.createProduct("name",1,"100","imageurl","off","desc");
  print(poduct.imageUrl);