Null Reference Exception for Class Lists

Question

I am new to programming and am running into an issue when creating a class with a list property of another class and then accessing it in main. I am getting the exception \"

Answer 1

Your problem is with public List bookList { get; set; } in your BookList class; you've never initialized it. You can do this, for example, from within the constructor:

class BookList
{
    public List bookList { get; set; }

    public BookList
    {
        bookList = new List();
    }
}

Please note: properties should always be named with Pascal casing, i.e. all letters uppercase: BookList not bookList.

Also, since it doesn't really make sense to replace your BookList with another instance of List, I would suggest you set the access modifier on the setter to private so it can only be initialized once, i.e. in the constructor:

public List bookList { get; private set; } // notice the "private" set