参数异常“具有相同密钥的项目已被添加” [英] Argument Exception "Item with Same Key has already been added"

问题描述

我继续使用以下代码发生错误：

 字典< string，string> rct3Features = new Dictionary< string，string>（）; 
字典< string，string> rct4Features = new Dictionary< string，string>（）; 
 
 foreach（rct3Lines中的字符串）
 {
 string [] items = line.Split（new String [] {}，2，StringSplitOptions.None） 
 
 rct3Features.Add（items [0]，items [1]）; 
 
 ////打印出字典（查看是否可以使用）
 // foreach（rct3Features中的KeyValuePair< string，string>项目）
 // {
 // Console.WriteLine（item.Key ++ item.Value）; 
 //} 
 
} 
  

错误会抛出一个 ArgumentException 说，

已经添加了具有相同密钥的项目。

我不确定几次Google搜索如何解决这个问题。

稍后在代码中，我需要访问比较函数的字典：

  Compare4To3（rct4Features，rct3Features）; 
 
 public static void Compare4To3（Dictionary< string，string> dictionaryOne，Dictionary< string，string> dictionaryTwo）
 {
 // foreach（dictionaryOne中的字符串项）
 // {
 
 //打印出字典（查看是否有效）
 foreach（KeyValuePair< dictionaryOne中的string>项目）
 {
 Console.WriteLine（item.Key ++ item.Value）; 
} 
 
 // if（dictionaryTwo.ContainsKey（dictionaryOne.Keys）
 // {
 // Console.Write（True）; 
 //} 
 // else 
 // {
 // Console.Write（False）; 
 //} 
 //} 
} 
  

此函数未完成，但我正在尝试解决此异常。方法我可以解决这个异常错误，并保持访问该字典与此功能一起使用？谢谢

解决方案

此错误是字典键是唯一的，你不能有多个相同的键。要解决这个问题，你应该修改你的代码，如下所示：

 字典< string，string> rct3Features = new Dictionary< string，string>（）; 
字典< string，string> rct4Features = new Dictionary< string，string>（）; 
 
 foreach（rct3Lines中的字符串）
 {
s tring [] items = line.Split（new String [] {}，2，StringSplitOptions.None）; 
 
如果（！rct3Features.ContainsKey（items [0]））
 {
 rct3Features.Add（items [0]，items [1]）; 
} 
 
 ////打印出字典（查看是否有效）
 // foreach（rct3Features中的KeyValuePair< string，string>项）
 // {
 // Console.WriteLine（item.Key ++ item.Value）; 
 //} 
} 
  

这个简单的 if 语句确保只有当Key（ items [0] ））尚未存在时，才尝试向Dictionary添加新条目。 / p>

I keep getting an error with the following code:

Dictionary<string, string> rct3Features = new Dictionary<string, string>();
Dictionary<string, string> rct4Features = new Dictionary<string, string>();

foreach (string line in rct3Lines) 
{
    string[] items = line.Split(new String[] { " " }, 2, StringSplitOptions.None);

    rct3Features.Add(items[0], items[1]);

    ////To print out the dictionary (to see if it works)
    //foreach (KeyValuePair<string, string> item in rct3Features)
    //{
    //    Console.WriteLine(item.Key + " " + item.Value);
    //}

}

The error throws an ArgumentException saying,

"An item with the same key has already been added."

I am unsure after several Google searches how to fix this.

Later in the code I need to access the dictionary for a compare function:

Compare4To3(rct4Features, rct3Features);

public static void Compare4To3(Dictionary<string, string> dictionaryOne, Dictionary<string, string> dictionaryTwo)
{
    //foreach (string item in dictionaryOne)
    //{

    //To print out the dictionary (to see if it works)
    foreach (KeyValuePair<string, string> item in dictionaryOne)
    {
        Console.WriteLine(item.Key + " " + item.Value);
    }

        //if (dictionaryTwo.ContainsKey(dictionaryOne.Keys)
        //{
        //    Console.Write("True");
        //}
        //else
        //{
        //    Console.Write("False");
        //}
    //}
}

This function isn't completed, but I am trying to resolve this exception. What are the ways I can fix this exception error, and keep access to the dictionary for use with this function? Thank you

解决方案

This error is fairly self-explanatory. Dictionary keys are unique and you cannot have more than one of the same key. To fix this, you should modify your code like so:

Dictionary<string, string> rct3Features = new Dictionary<string, string>();
Dictionary<string, string> rct4Features = new Dictionary<string, string>();

foreach (string line in rct3Lines) 
{
    string[] items = line.Split(new String[] { " " }, 2, StringSplitOptions.None);

    if (!rct3Features.ContainsKey(items[0]))
    {
        rct3Features.Add(items[0], items[1]);
    }

    ////To print out the dictionary (to see if it works)
    //foreach (KeyValuePair<string, string> item in rct3Features)
    //{
    //    Console.WriteLine(item.Key + " " + item.Value);
    //}
}

This simple if statement ensures that you are only attempting to add a new entry to the Dictionary when the Key (items[0]) is not already present.

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