问

Why is it possible to write constructor for an abstract class in C#?
As far as I know we can‘t instantiate an abstract class.. so what is it for?
You can‘t instantiate the class, right?

答

Because there might be a standard way you want to instantiate data in the abstract class. That way you can have classes that inherit from that class call the base constructor.

public abstract class A
{

    private string data;

    protected A(string myString)
    {
        data = myString;
    }

}

public class B : A
{
    public B(string myString) : base(myString)
    {

    }

}

原文链接

抽象类为什么可以有构造函数？- Constructor of an abstract class in C#（转载）