blocks|key|1645763|text|只需使用以下命令：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1645764|List<string>+list+=+new+List<string>()+{+"single+value"+};|code-block|syntax|javascript|1645765|您甚至可以省略()大括号：|1645766|List<string>+list+=+new+List<string>+{+"single+value"+};|1645767|更新:当然，这也适用于多个条目：|1645768|List<string>+list+=+new+List<string>+{+"value1",+"value2",+...+};|1645769|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

Simply use this:

<pre><code>List&lt;string&gt; list = new List&lt;string&gt;() { "single value" };
</code></pre>

You can even omit the () braces:

<pre><code>List&lt;string&gt; list = new List&lt;string&gt; { "single value" };
</code></pre>

Update: of course this also works for more than one entry:

<pre><code>List&lt;string&gt; list = new List&lt;string&gt; { "value1", "value2", ... };
</code></pre>

blocks|key|1646014|text|var+list+=+new+List<string>(1)+{+"hello"+};|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1646015|与其他人发布的内容非常相似，只是它确保最初只为单个项目分配空间。|unstyled|1646016|当然，如果你知道以后你会添加一大堆东西，这可能不是一个好主意，但仍然值得一提。|1646017|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|L|8|@]|9|@]|A|$]]|$1|G|3|H|5|F|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|F|7|N|8|@]|9|@]|A|$]]]|J|$]]

<pre><code>var list = new List&lt;string&gt;(1) { "hello" };
</code></pre>

Very similar to what others have posted, except that it makes sure to only allocate space for the single item initially.

Of course, if you know you'll be adding a bunch of stuff later it may not be a good idea, but still worth mentioning once.

blocks|key|1645844|text|Michael使用扩展方法的想法带来了更简单的东西：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1645845|public+static+List<T>+InList<T>(this+T+item)
{
++++return+new+List<T>+{+item+};
}|code-block|syntax|javascript|1645846|所以你可以这样做：|1645847|List<string>+foo+=+"Hello".InList();|1645848|我不确定我是不是喜欢，提醒你...|1645849|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Michael's idea of using extension methods leads to something even simpler:

<pre><code>public static List&lt;T&gt; InList&lt;T&gt;(this T item)
{
 return new List&lt;T&gt; { item };
}
</code></pre>

So you could do this:

<pre><code>List&lt;string&gt; foo = "Hello".InList();
</code></pre>

I'm not sure whether I like it or not, mind you...

blocks|key|1431010|text|与我之前的答案不同，基于对Google+Java+Collections的暴露|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1431011|public+static+class+Lists
{
++++public+static+List<T>+Of<T>(T+item)
++++{
++++++++return+new+List<T>+{+item+};
++++}
}|code-block|syntax|javascript|1431012|然后：|1431013|List<string>+x+=+Lists.Of("Hello");|1431014|我建议你去看看GJC+--里面有很多有趣的东西。(就我个人而言，我会忽略"alpha“标签--它只是一个开源版本，即"alpha”，它基于一个非常稳定且大量使用的内部API。)|1431015|entityMap|0|LINK|mutability|MUTABLE|url|http://code.google.com/p/google-collections/^0|D|N|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@$A|X|B|Y|1|Z]]|C|$]]|$1|D|3|E|5|F|7|10|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|11|8|@]|9|@]|C|$]]|$1|K|3|L|5|F|7|12|8|@]|9|@]|C|$G|H]]|$1|M|3|N|5|6|7|13|8|@]|9|@]|C|$]]|$1|O|3|-4|5|6|7|14|8|@]|9|@]|C|$]]]|P|$Q|$5|R|S|T|C|$U|V]]]]

A different answer to my earlier one, based on exposure to the <a href="http://code.google.com/p/google-collections/" rel="noreferrer">Google Java Collections</a>:

<pre><code>public static class Lists
{
 public static List&lt;T&gt; Of&lt;T&gt;(T item)
 {
 return new List&lt;T&gt; { item };
 }
}
</code></pre>

Then:

<pre><code>List&lt;string&gt; x = Lists.Of("Hello");
</code></pre>

I advise checking out the GJC - it's got lots of interesting stuff in. (Personally I'd ignore the "alpha" tag - it's only the open source version which is "alpha" and it's based on a very stable and heavily used internal API.)

blocks|key|1646254|text|new[]+{+"item"+}.ToList();|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1646255|它比|unstyled|1646256|new+List<string>+{+"item"+};|1646257|而且您不必指定类型。|1646258|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|N|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$B|C]]|$1|I|3|J|5|F|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|F|7|Q|8|@]|9|@]|A|$]]]|L|$]]

<pre><code>new[] { "item" }.ToList();
</code></pre>

It's shorter than

<pre><code>new List&lt;string&gt; { "item" };
</code></pre>

and you don't have to specify the type.

blocks|key|1431341|text|还有另一种方式，可以在"C#/.Net小奇迹“上找到(不幸的是，这个网站已经不存在了)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1431342|Enumerable.Repeat("value",1).ToList()|code-block|syntax|javascript|1431343|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Yet another way, found on "C#/.Net Little wonders" (unfortunately, the site doesn't exist anymore):

<pre><code>Enumerable.Repeat("value",1).ToList()
</code></pre>

blocks|key|1431125|text|对于java中可枚举的单个项，它将是Collections.singleton("string")；|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1431126|在c#中，这将比一个新的列表更有效：|1431127|public+class+SingleEnumerator<T>+:+IEnumerable<T>
{
++++private+readonly+T+m_Value;

++++public+SingleEnumerator(T+value)
++++{
++++++++m_Value+=+value;
++++}

++++public+IEnumerator<T>+GetEnumerator()
++++{
++++++++yield+return+m_Value;
++++}

++++IEnumerator+IEnumerable.GetEnumerator()
++++{
++++++++yield+return+m_Value;
++++}
}|code-block|syntax|javascript|1431128|但是有没有更简单的使用框架的方法呢？|1431129|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|O|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

For a single item enumerable in java it would be Collections.singleton("string");

In c# this is going to be more efficient than a new List:

<pre><code>public class SingleEnumerator&lt;T&gt; : IEnumerable&lt;T&gt;
{
 private readonly T m_Value;

 public SingleEnumerator(T value)
 {
 m_Value = value;
 }

 public IEnumerator&lt;T&gt; GetEnumerator()
 {
 yield return m_Value;
 }

 IEnumerator IEnumerable.GetEnumerator()
 {
 yield return m_Value;
 }
}
</code></pre>

but is there a simpler way using the framework?

blocks|key|1431205|text|我有一个小函数：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1431206|public+static+class+CoreUtil
{++++
++++public+static+IEnumerable<T>+ToEnumerable<T>(params+T[]+items)
++++{
++++++++return+items;
++++}
}|code-block|syntax|javascript|1431207|因为它没有规定一个具体的返回类型，所以它是如此的通用，所以我到处使用它。您的代码将如下所示|1431208|CoreUtil.ToEnumerable("title").ToList();|1431209|当然，它也允许|1431210|CoreUtil.ToEnumerable("title1",+"title2",+"title3").ToArray();|1431211|当我必须在LINQ语句的输出中附加/预先添加一项时，我经常使用它。例如，要将空白项添加到选择列表中：|1431212|CoreUtil.ToEnumerable("").Concat(context.TrialTypes.Select(t+=>+t.Name))|1431213|保存一些ToList()和Add语句。|offset|length|style|CODE|1431214|(回答晚了，但我偶然发现了这个老东西，并认为这可能是有帮助的)|1431215|entityMap^0|0|0|0|0|0|0|0|0|4|8|D|3|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|14|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|15|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|16|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|17|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|18|8|@]|9|@]|A|$]]|$1|Q|3|R|5|D|7|19|8|@]|9|@]|A|$E|F]]|$1|S|3|T|5|6|7|1A|8|@$U|1B|V|1C|W|X]|$U|1D|V|1E|W|X]]|9|@]|A|$]]|$1|Y|3|Z|5|6|7|1F|8|@]|9|@]|A|$]]|$1|10|3|-4|5|6|7|1G|8|@]|9|@]|A|$]]]|11|$]]

I've got this little function:

<pre><code>public static class CoreUtil
{ 
 public static IEnumerable&lt;T&gt; ToEnumerable&lt;T&gt;(params T[] items)
 {
 return items;
 }
}
</code></pre>

Since it doesn't prescribe a concrete return type this is so generic that I use it all over the place. Your code would look like

<pre><code>CoreUtil.ToEnumerable("title").ToList();
</code></pre>

But of course it also allows

<pre><code>CoreUtil.ToEnumerable("title1", "title2", "title3").ToArray();
</code></pre>

I often use it in when I have to append/prepend one item to the output of a LINQ statement. For instance to add a blank item to a selection list:

<pre><code>CoreUtil.ToEnumerable("").Concat(context.TrialTypes.Select(t =&gt; t.Name))
</code></pre>

Saves a few <code>ToList()</code> and <code>Add</code> statements.

(Late answer, but I stumbled upon this oldie and thought this could be helpful)

blocks|key|1430906|text|你也可以这样做|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1430907|new+List<string>()+{+"string+here"+};|code-block|syntax|javascript|1430908|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You can also do

<pre><code>new List&lt;string&gt;() { "string here" };
</code></pre>

blocks|key|1430971|text|我就会这么做|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1430972|var+list+=+new+List<string>+{+"hello"+};|code-block|syntax|javascript|1430973|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I would just do 

<pre><code>var list = new List&lt;string&gt; { "hello" };
</code></pre>

blocks|key|1431443|text|如果有人登陆这个页面，并试图添加对象而不是字符串，那么这对我来说是有效的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1431444|new+List<myObj>+{+new+myObj{propertName=propstryValue+}
,+new+myObj{propertName=propstryValue+},+new+myObj{propertName=propstryValue+}
};|code-block|syntax|javascript|1431445|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If someone landed on this page and trying to add object instead of string, then this worked for me.
<pre><code>new List&lt;myObj&gt; { new myObj{propertName=propstryValue }
, new myObj{propertName=propstryValue }, new myObj{propertName=propstryValue }
};
</code></pre>

blocks|key|1431399|text|您需要从List<>类创建一个继承者|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1431400|++++public+class+SingletonList<T>+:+List<T>
++++{
++++++++public+SingletonList(T+element)+:+base(1)
++++++++{
++++++++++++this.Add(element);
++++++++}
++++}|code-block|syntax|javascript|1431401|并且您可以使用它来代替基类List<>|1431402|var+singletonList+=+new+SingletonList<string>("Hello+World!");|1431403|entityMap^0|4|6|0|0|D|6|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|P|$]]

You need to create an inheritor from the <code>List&lt;&gt;</code> class
<pre><code> public class SingletonList&lt;T&gt; : List&lt;T&gt;
 {
 public SingletonList(T element) : base(1)
 {
 this.Add(element);
 }
 }
</code></pre>
and you can use it instead of the base <code>List&lt;&gt;</code> class
<pre><code>var singletonList = new SingletonList&lt;string&gt;(&quot;Hello World!&quot;);
</code></pre>

In C#, is there an inline shortcut to instantiate a List&lt;T&gt; with only one item.

I'm currently doing:

<pre><code>new List&lt;string&gt;( new string[] { "title" } ))
</code></pre>

Having this code everywhere reduces readability. I've thought of using a utility method like this:

<pre><code>public static List&lt;T&gt; SingleItemList&lt;T&gt;( T value )
{
 return (new List&lt;T&gt;( new T[] { value } ));
}
</code></pre>

So I could do:

<pre><code>SingleItemList("title");
</code></pre>

Is there a shorter / cleaner way?

Thanks.

Shortcut for creating single item list in C#

在C#中，是否有一个内联快捷方式来实例化一个只有一项的列表。我目前正在做的是：new List<string>( new string[] { "title" } ))到处都是这段代码会降低可读性。我曾想过使用这样的实用方法：public static List<T> SingleItemList<T>( T value ){ return (new List<T>( new T[] { v

问在C#中创建单项列表的快捷方式
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