How Can I Instantiate Generic Types in C# Using Type Variables?

Create a generic type instance using a variable of the containing type

In C#, it may seem counterintuitive that you cannot instantiate a generic type directly using a variable of the containing type. The following code illustrates the problem:

<code class="language-c#">Type k = typeof(double);
List<k> lst = new List<k>(); // 编译错误</code>

This code does not compile because it attempts to use the variable k to specify a generic type. However, there is a workaround that can be used to achieve the desired functionality.

To create a generic type instance using a variable of the containing type, you can leverage reflection and Activator.CreateInstance():

<code class="language-c#">var genericListType = typeof(List<>);
var specificListType = genericListType.MakeGenericType(typeof(double));
var list = Activator.CreateInstance(specificListType);</code>

This code works like this:

1. genericListType Gets the generic List<> type definition.
2. MakeGenericType() gets the generic type definition and specifies the actual type parameters (double in this case).
3. Activator.CreateInstance() Instantiates a specific generic type using the specified type parameters.

The above is the detailed content of How Can I Instantiate Generic Types in C# Using Type Variables?. For more information, please follow other related articles on the PHP Chinese website!