Recursively adding node to end of linkedlist

Question

I am trying to recursively append an element to the end of a Linked List .However, Nothing seems to be added. I use a private helper method so I can use the reference as a parameter. I don't run into any exceptions, however, my test cases show that nothing at all has been added to the list! I have no idea what I'm doing wrong, and have no idea where to start. Your help is very appreciated.

public void addLast(E element) {
    addLast(element,first);
}

private void addLast(E element, Node ref) {
    if (ref == null) {
        ref = new Node(element);
        n++;
            } else if (ref.next == null) {
                    ref.next = new Node(element);
                    n++;
    } else {
        addLast(element, ref.next);
    }
}

First of all, what is n? Is your problem that the list is always empty? If yes, then try changing 'ref = new Node(element)' under the first if block to first = new Node(element), where 'first' is your list's head pointer. — slider
– slider, Commented Nov 2, 2013 at 3:20
Could you please post an example that results in an empty LinkedList? — vandale
– vandale, Commented Nov 2, 2013 at 3:23

Sourabh · Accepted Answer · 2013-11-02 05:21:33Z

6

You have to do something like this. Refer this link for explanation.

private Node addLast(E element, Node ref) {
    if (ref == null) {
        ref = new Node(element);

    } else {
        ref.next = addLast(element, ref.next);
    }
    return ref;
}

answered Nov 2, 2013 at 5:21

Sourabh

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Comments

Steve P. · Accepted Answer · 2013-11-02 03:20:37Z

1

private void addLast(Node node){

   while(root.next != null){
            root = root.next;

            if (root.next == null){
                root.next = node;
                break;
            }
    }
}

Not recursive because you don't need it...

edited Nov 2, 2013 at 3:20

Steve P.

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answered Nov 2, 2013 at 3:15

William Falcon

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