How to search LinkedList<T> collection?

Question

I have a LinkedList<T> object where T is an arbitrary object which has a property named ID. I want search my collection using ID as search criteria.

Now I know I can search it using a while loop:

LinkedListNode<MyObject> element = myObject.First;
while (element != myObject.Last)
{
    if (element.Value.ID == myID)
    break;

    element = element.Next;
}

But I'm wondering if there is a more elegant solution. Note that I need LinkedListNode<T> as a result in order to navigate the list from there.

Answer 1

Will this give the result you expect?

Use @MartinLiversage answer and expand it to use the Find method which is part of the LinkedList<T>

int id = 1;
LinkedListNode<IHaveID> nodes = null;
LinkedList<IHaveID> testList = new LinkedList<IHaveID>();

var item = testList.FirstOrDefault(x => x.ID == id);
if(item != null)
{
    nodes = testList.Find(item);
}

Answer 2

You can write an extension method to get you a sequence of the nodes and search that:

public static IEnumerable<LinkedListNode<T>> Nodes<T>(this LinkedList<T> list)
{
    for (var node = list.First; node != null; node = node.Next)
    {
        yield return node;
    }
}

then you can do

var matchingNode = list.Nodes().FirstOrDefault(n => n.Value.Id == myId);

Answer 3

Same idea as Lee, but simpler code:

    public static IEnumerable<LinkedListNode<T>> Nodes<T>(this LinkedList<T> list)
    {
        var node = list.First;
        while (node != null)
        {
            yield return node;
            node = node.Next;
        }
    }

EDIT

No need to use LINQ or extension methods. Simply use .Find() - it returns a LinkedListNode

var node = list.Find(5);

Note: For this to work your model with the id would need to override object.Equals to compare ID's (and therefore object.GetHashCode)