C# - 如何将 List<T> 作为参数传递给委托

Question

本质上我想做的是创建一个委托，我想将函数传递给一个方法——它将获取产品对象列表并执行某些计算。

很遗憾，我收到一条错误消息

main.cs(11,40)：错误 CS0120：需要对象引用才能访问非静态成员“MainClass.MyDelegate(System.Collections.Generic.List)” 编译失败：1 个错误，0 个警告编译器退出状态 1

我的问题是为什么我很难将列表传递给代表 - 我做错了什么？

谢谢你和亲切的问候


using System;
using System.Collections.Generic;
using System.Collections;

class MainClass {
  public static void Main (string[] args) {
    Console.WriteLine ("Hello World");
    MyCart MyBasket =  new MyCart();
    MyBasket.Initialize();
    //Console.WriteLine(MyBasket.basket.Count);
    MyBasket.BuyItem("Iphone", 300.3m, MyDelegate );
  }

  public void MyDelegate (List<Product> e){
    // this is where i am performing my delegate
    if (e.Count > 2)
    {
      Console.WriteLine($"This is delegate Talking our current Cart has more than 2 items inside, in fact the count is  {e.Count}");
    }
    else

    {
      Console.WriteLine($"This is delegate Talking our current Cart has less than 2 items inside, in fact the count is  {e.Count}");
    }
  }
}

public class MyCart
{
//public delegate void ObjectCheck(List<Product> basket) ;

public List<Product> basket = new List<Product>();
public delegate void ObjectCheck(List<Product> basket) ;
public void Initialize (){
  // this is our Cart Class constructor
  basket.Add(new Product { ItemName = "Book", ItemPrice = 4.9m });
  basket.Add(new Product { ItemName = "Milk", ItemPrice = 3.5m });
}

public void BuyItem (string i, decimal p, ObjectCheck mymethod)
{
  basket.Add(new Product {ItemName = i, ItemPrice = p});

  mymethod(basket);

}
}

Answer 1

您遇到此错误是因为 MyDelegate 是一个实例方法（上面没有 static 关键字）并且它正在 static 上下文中使用（Main).要修复错误，您需要这样声明 MyDelegate ：

public static void MyDelegate (List<Product> e)
{
    // do some stuff
}

C# - 如何将 List<T> 作为参数传递给委托

C# - How to pass List<T> to a delegate as parameter

c#

generics

parameters

delegates

list