Question

How can I get next element of element to which I have reference in some collection e.g. List<T> ?

I am not talking about any loops, etc. I want get just one next (or previous) element

Answer 1

It’s not the most performant, but it should work. You can even make it an extension method.

    public static T GetNext<T>(IList<T> collection, T value )
    {
        int nextIndex = collection.IndexOf(value) + 1;
        if (nextIndex < collection.Count)
        {
            return collection[nextIndex];
        }
        else
        {
            return value; //Or throw an exception
        }
    }

And you use it like this:

        var list = new List<string> {"A", "B", "C", "D"};
        string current = "B";
        string next = GetNext(list, current);
        Console.WriteLine(next); //Prints C