how to get a node by its position in the list in java? (not the value, the whole node)

Question

I have a linked list and a position of a node, and I need to get the node itself from the list (not only its value). Is there a func in java that does that? if not, can you send a piece of code that does that?

Thanks.

Answer 1

public class Node {
    public int data;
    public Node next;

    public Node(int _data) {
        this.data = _data;
        this.next = null;
    }

    public String toString() {
        return (Integer.toString(data));
    }
}




public class LinkedList {

    public static void main(String args[]) {
        LinkedList linkedlist = new LinkedList();

        linkedlist.InsertNode(15);
        linkedlist.InsertNode(20);
        linkedlist.InsertNode(25);
        linkedlist.InsertNode(30);
        linkedlist.InsertNode(35);
        linkedlist.showLinkedList();
        System.out.println("\n");
           Node retnode = linkedlist.retPosNode(2);
            System.out.println("REturn Node: "+retnode.data);
            linkedlist.showLinkedList();


    }

    Node head;

    public void InsertNode(int data) {
        Node node = new Node(data);

        if (head == null) {
            head = node;
        } else {
            Node n = head;
            while (n.next != null) {
                n = n.next;
            }
            n.next = node;
        }
    }
    public Node retPosNode(int pos) {
    Node curr = head;
    Node prev= null;
    Node retPos= null;
    int i=0;
    if (curr==null)
    return null;

    while(curr!=null) {
        if(i==pos) {
            if(i!=0) {
            retPos = curr;
            prev.next= curr.next;
            curr = curr.next;
            }
            else {
                retPos = curr;
                head=  curr.next;
                curr = curr.next;
            }
        }
        prev= curr;
        curr = curr.next;
        i++;
    }
    return retPos;

    }

    public void showLinkedList() {
        Node node = head;
        while (node != null) {
            System.out.print(node.data + " ");
            node = node.next;
        }
    }   
}

Answer 2

No. Java's LinkedList doesn't allow you to work directly on the nodes.

If you need an O(1) “pointer”, you can use a ListIterator: list.listIterator()

If your linked list is a custom implementation, I'm 99% sure it's your homework and you should do it yourself.