C# Generic Class<T>

Question

How can I add a generic Type to my list? I tried to create an object of T but this doesn't work neither.

class Bar<T> where T : IDrink
{
    List<T> storage = new List<T>();

    public void CreateDrink()
    {
        storage.Add(T); //<- This doesn't work
    }
}

Answer 1

T is a type not an instance of that type. So you need a parameter in CreateDrink or use a factory method that returns a new instance of T .

If you want to create an instance the generic constraint must include new()

class Bar<T> where T : IDrink, new()
{
    List<T> storage = new List<T>();

    public void CreateDrink()
    {
        storage.Add(new T()); 
    }
}

The new constraint specifies that any type argument in a generic class declaration must have a public parameterless constructor. To use the new constraint, the type cannot be abstract.

Answer 2

你可以这样做：

storage.Add(Activator.CreateInstance<T>());