There is a class

public class KeyGroup { public string key { get; set; } public bool used { get; set; } public List<string> url { get; set; } }

Create an instance of the class.

 KeyGroup keyGroup = new KeyGroup(); keyGroup.key = "ya.ru"; // это работает keyGroup.url.AddRange(list); // здесь ошибку выдает keyGroup.url=list; // А так работает

What's wrong?

    1 answer 1

    Fields of a reference type are initialized by the compiler to null .

     public class KeyGroup { public string key { get; set; } public bool used { get; set; } public List<string> url { get; set; } public KeyGroup() { url = new List<string>(); } }