如何初始化字符串列表（List<string> ) 有很多字符串值

Question

How is it possible to initialize (with a C# initializer) a list of strings? I have tried with the example below but it's not working.

List<string> optionList = new List<string>
{
    "AdditionalCardPersonAddressType","AutomaticRaiseCreditLimit","CardDeliveryTimeWeekDay"
}();

Answer 1

Just remove () at the end.

List<string> optionList = new List<string>
            { "AdditionalCardPersonAdressType", /* rest of elements */ };

Answer 2

List<string> mylist = new List<string>(new string[] { "element1", "element2", "element3" });

Answer 3

You haven't really asked a question, but the code should be

List<string> optionList = new List<string> { "string1", "string2", ..., "stringN"}; 

ie no trailing () after the list.

Answer 4

var animals = new List<string> { "bird", "dog" };
List<string> animals= new List<string> { "bird", "dog" };

Above two are the shortest ways, please see https://www.dotnetperls.com/list

Answer 5

Your function is just fine but isn't working because you put the () after the last } . If you move the () to the top just next to new List<string>() the error stops.

Sample below:

List<string> optionList = new List<string>()
{
    "AdditionalCardPersonAdressType","AutomaticRaiseCreditLimit","CardDeliveryTimeWeekDay"
};

Answer 6

This is how you initialize and also you can use List.Add() in case you want to make it more dynamic.

List<string> optionList = new List<string> {"AdditionalCardPersonAdressType"};
optionList.Add("AutomaticRaiseCreditLimit");
optionList.Add("CardDeliveryTimeWeekDay");

In this way, if you are taking values in from IO, you can add it to a dynamically allocated list.

Answer 7

像这样移动圆括号：

var optionList = new List<string>(){"AdditionalCardPersonAdressType","AutomaticRaiseCreditLimit","CardDeliveryTimeWeekDay"};

Answer 8

How is it possible to initialize (with a C# initializer) a list of strings? I have tried with the example below but it's not working.

List<string> optionList = new List<string>
{
    "AdditionalCardPersonAddressType","AutomaticRaiseCreditLimit","CardDeliveryTimeWeekDay"
}();

Answer 9

There is something else that you might be missing that hasn't been mentioned. I think it might be the problem you are having as I suspect you already tried removing the trailing () and still got an error.

First, like others have mentioned here, in your example you do need to remove the trailing ();

But, also, note that List<> is in the System.Collections.Generic namespace.

So, you need to do one of the following two options: [#1 below is probably the more preferred option]

(1) Include the use of the namespace at the top of your code with: using System.Collections.Generic;

or

(2) Put the fully qualified path to List in your declaration.

System.Collections.Generic.List optList=new System.Collections.Generic.List { "AdditionalCardPersonAddressType","AutomaticRaiseCreditLimit","CardDeliveryTimeWeekDay" };

Hope that helps.

The error message you receive when you implement List correctly but don't include the System.Collections.Generic namespace is misleading and not helpful:

"Compiler Error CS0308: The non-generic type List cannot be used with type arguments."

PS - It gives this unhelpful error because if you don't specify that you intend to use System.Collections.Generic.List the compiler assumes you are trying to use System.Windows.Documents.List.

Answer 10

One really cool feature is that list initializer works just fine with custom classes too: you have just to implement the IEnumerable interface and have a method called Add .

So for example if you have a custom class like this:

class MyCustomCollection : System.Collections.IEnumerable
{
    List<string> _items = new List<string>();

    public void Add(string item)
    {
        _items.Add(item);
    }

    public IEnumerator GetEnumerator()
    {
        return _items.GetEnumerator();
    }
}

this will work:

var myTestCollection = new MyCustomCollection()
{
    "item1",
    "item2"
}

Answer 11

我已经看到了内容标签 C#，但如果有人可以使用 Java（这里的搜索词相同）：

List<String> mylist = Arrays.asList(new String[] {"element1", "element2", "element3" }.clone());

Answer 12

The right way to initialize along with declaration is :

List<string> optionList = new List<string>()
{
    "AdditionalCardPersonAdressType","AutomaticRaiseCreditLimit","CardDeliveryTimeWeekDay"
};

Answer 13

If you are using C# 9.0 and up you can use the new feature target-typed new expressions Link

Example:

List<string> stringList = new(){"item1","item2", "item3"} ;

Answer 14

How is it possible to initialize (with a C# initializer) a list of strings? I have tried with the example below but it's not working.

List<string> optionList = new List<string>
{
    "AdditionalCardPersonAddressType","AutomaticRaiseCreditLimit","CardDeliveryTimeWeekDay"
}();

Answer 15

This is how you would do it.

 List <string> list1 = new List <string>();

Do Not Forget to add

 using System.Collections.Generic;