参数例外：“已添加具有相同密钥的项目” [英] Argument Exception: "An item with the same key has already been added"

问题描述

我有一个应用程序在我尝试添加项目时挂起。



我收到运行时错误：



已添加具有相同密钥的项目。

I have an application which got hung when i tried to add items to it.

I get a runtime error:

An item with the same key has already been added.

  private class ProductUpdate
        {
            public int Index = 0;
            public string ProductCode;
        }
private void UpdateProduct( List<string> account, string userEmail, 
List<Product> products )
   {
Dictionary<string, ProductUpdate> productUpdateDictionary = new Dictionary<string, ProductUpdate>();

            for ( int i = 0; i < products.Count; i++ )
            {
       productUpdateDictionary.Add( products[i].code, new ProductUpdate { Index = i, ProductCode = products[i].code } );
            }
}

我不知道如何解决这个问题，任何机构都有任何建议

非常感谢！

I don't know how to solve this issue ,any body has any suggestion
Thanks a lot!

推荐答案

您发布的代码中没有错误。问题可能是概念类型，也可能代码是调用 UpdateProduct（..）的代码。



In这一行：

There's no bug in the code that you posted. The problem is either of conceptual kind or lies in the code that calls UpdateProduct(..).

In this line:

productUpdateDictionary.Add( products[i].code, new ProductUpdate { Index = i, ProductCode = products[i].code } );

你的代码正在填充一个Dictionary。字典只允许添加唯一键。方法参数 List< Product>中的一个或多个 Product s产品具有相同的代码 s，这就是这里例外的原因。


修改：<>麻烦

your code is populating a Dictionary. A Dictionary only ever allows unique keys to be added. One or more Products in the method-argument List<Product> products have identical codes and that's the cause of the exception here.

<> troubles

请阅读我对这个问题的评论。



A 字典 [ ^ ]不允许两次添加相同的值。您需要通过添加尝试...抓住......最后 [ ^ ]阻止。

Please, read my comment to the question.

A dictionary[^] does not allow to add the same value twice. You need to handle it by adding Try... Catch... Finally[^] block.

在为密钥添加值之前，您必须检查密钥是否已存在。你必须这样做。

You have to check if a key already exists before adding a value for the key. You have to do as follows.

if (!productUpdateDictionary.Contains(products[i].code)){
    productUpdateDictionary.Add(products[i].code, new ProductUpdate { Index = i, ProductCode = products[i].code });
}

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