How to insert Object at specified Index in Java Linked List

Trying to insert an object at a specified index in a linked list java class. Not too sure how too implement this though.

Here is an example of the parameters for the method and what i have so far(doesn't work):

  void insertAtIndex(int idx, Shape data){
    if (idx == 0) {
        //insert the new Shape at the beginning of the list
        insertAtBeginning(data);
    }else{

        Node temp = head;
        for(int i = 0; i < idx - 1; i++)
            temp = temp.getNext();
        Node next = new Node(data);
        next = temp.getNext();
        temp = next;

    }
}

subclass for Node:

public Node(Shape data){
    //Make next point to null
    next = null;
    this.data = data;
}

// another Node constructor if we want to specify the node to point to.
public Node(Shape dataVal, Node nextVal){
    next = nextVal;
    data = dataVal;
}

//Getter for data
public Shape getData(){
    return data;
}

//Setter for data
public void setData(Shape data){
    this.data = data;
}

//Getter for next
public Node getNext() {
    return next;
}

//Setter for next
public void setNext(Node next) {
    this.next = next;
}

linked list class:

public class ShapeLinkedList {

public Node head; //head is first node in linked list
public Node tail; //tail is last node in linked list

public ShapeLinkedList(){}

public ShapeLinkedList(Node head){
    head = null;
    tail = null;
}

public boolean isEmpty(){
    return length() == 0;
}