[英]how to use classes in flutter/dart
i have created a class of products.我创建了一个 class 产品。 then i created an empty list of products named cart.
然后我创建了一个名为购物车的空产品列表。 then i am trying to add products to this cart and printing it, it is showing instance of product on console.
然后我尝试将产品添加到此购物车并打印它,它在控制台上显示产品实例。
class product {
late String name;
late int id,size,price;
product(String name,int id,int size,int price){
this.name=name;
this.size=size;
this.id=id;
this.price=price;
}
}
List cart=[];列出购物车=[];
wishlist page:愿望清单页面:
class wishlist extends StatefulWidget {
const wishlist({Key? key}) : super(key: key);
@override
State<wishlist> createState() => _wishlistState();
}
class _wishlistState extends State<wishlist> {
late String category;
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
leading: BackButton(
color: Colors.black,
),
backgroundColor: Color(0xFF45F1B9),
title: Center(
child: Text('Categories',
style: TextStyle(
color: Colors.black
),
),
),
),
backgroundColor: Colors.white,
body: ListView.builder(
itemCount: categories.length,
itemBuilder:(BuildContext context,int index){
return Card(child: ListTile(title: Text(categories[index].name,
),
onTap: (){
Navigator.push(
context,
MaterialPageRoute(builder: (context) => cpproducts1(categories[index].prod),),
);
},
),
);
},
),
);
}
}
second page'cproducts':第二页'cproducts':
class cpproducts1 extends StatelessWidget {
late List<product> prod;
cpproducts1( this.prod, {Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.white,
body: ListView.builder(
itemCount:prod.length ,
itemBuilder:(BuildContext context,int index){
return Card(child: ListTile(title: Text(prod[index].name,),
trailing: Text('\$${prod[index].price}'),
onTap: (){
cart.add(prod[index]);
print(cart);
},
),
);
},
),
);
}
}
cart.add(prod[index]);
print(cart);
after these line run it says instance of product.在这些行运行之后,它会显示产品实例。
i need the products to be added to the cart list so i can use them我需要将产品添加到购物车列表中,以便我可以使用它们
does anybody know the answer to this.有没有人知道这个问题的答案。
You can create a constructor in a much Simpler way, and to know the actual value rather than Instance of Class you have to add override toString
method.您可以以更简单的方式创建构造函数,并且要知道实际值而不是 Class 的实例,您必须添加覆盖
toString
方法。
class Product {
const Product(this.name, this.id, this.size, this.price);
late final String name;
late final int id,size,price;
@override
String toString() => '$name, $id, $size, $price';
}
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