CODEWITHSUNDEEP
c#linked-list
Failed Scientist
Failed Scientist

Reputation: 2027

How to use LinkedList<T>.Find() method where T is an user-defined datatype (Objects)

The Find() method for LinkedList in C# works fine for strings, etc, but how to use it with structs, objects, etc?

Here is my code:

    {
        LinkedList<Item> TestLinkedList = new LinkedList<Item>();

        TestLinkedList.AddFirst(new Item(3, "Head n Shoulders"));

        TestLinkedList.AddAfter(TestLinkedList.First, new Item(45, "Dell"));

        //Get the 2nd node in the linklist

        Item c = new Item(3, "Head n Shoulders");

        LinkedListNode<Item> Node2 = TestLinkedList.Find(c);



        TestLinkedList.AddAfter((Node2), new Item(32, "Adidas"));

        foreach (Item i in TestLinkedList)
        {
            i.Print();
        }

        Console.ReadKey();
    }

Its returning NULL for the Node2. Am I making the mistake at not using the unique Hashcode etc?

Upvotes: 1

Views: 825

Answers (1)

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726619

In order for the Find to return the correct object, your Item class needs to override the Equals method. Of course you also need to override GetHashCode as well: although Find of LinkedList does not call GetHashCode, the two methods need to be changed together:

Types that override Equals(Object) must also override GetHashCode; otherwise, hash tables might not work correctly.

Upvotes: 2

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