how to create instance for a generic type in c#

Question

I need to create an parameterless instance for a Generic Class in C#.

How to do this.

Answer 1

You could add the : new() constraint:

void Foo<T>() where T : class, new() {
    T newT = new T();
    // do something shiny with newT
}

If you don't have the constraint, then Activator.CreateInstance<T> may help (minus the compile-time checking):

void Foo<T>() {
    T newT = Activator.CreateInstance<T>();
    // do something shiny with newT
}

If you mean you the type itself, then probably something like:

Type itemType = typeof(int);
IList list = (IList)Activator.CreateInstance(
         typeof(List<>).MakeGenericType(itemType));