Stack overflow from recursive toString function after swapping Linked List nodes

I am getting a stack overflow when I am using my recursive toString function on my Linked List after I am swapping the head node and another node in the middle of my Linked List. I am not sure as why this is happening and was hoping I can get some guidance of what is actually going on. It seems that before my swap function executes, the toString is working completely fine, but as soon as I swap the nodes I happen to get a stack overflow error in my recursive toString function.

My Linked List class:

public class LinkedList {
    //
    //Instance variable
    //
    private Node top;

    //
    //Instance and static methods below
    //

    //Accessor for the top Node
    public Node getTop() {
        return top;
    }

    public Node getPreviousNode(Node toFind) {
        //call getPreviousNodeRec() method
        if (top.equals(toFind))
            return null;
        else
            return getPreviousNodeRec(top, toFind);
    }

    private Node getPreviousNodeRec(Node start, Node toFind) {
        if (start.getLink().equals(toFind)) {
            return start;
        } else
            return getPreviousNodeRec(start.getLink(),toFind);
    }

    public void swap(Node n1, Node n2) {
        if (top.equals(n1)) {
            System.out.println("top equals n1");
            Node n2prev = getPreviousNode(n2);
            Node temp = n2.getLink();

            top = n2;
            top.setLink(n1.getLink());
            n1.setLink(temp);
            n2prev.setLink(n1);

            System.out.println("complete");
        }
    }

    public String toString() {
        if (top == null)
            return "There is nothing in the list!";
        else {
            String value = "";
            return toStringRec(top, value);
        }
    }

    private String toStringRec(Node start, String value) {
        if (start.getLink() != null) {
            value += start.getData()+"\n";
            return toStringRec(start.getLink(),value);
        } else
            return value+start.getData();
    }

    public void setTop(Node top) {
        this.top = top;
    }
}

Right now I am just trying to test my swap method for one case(top = n1).

This is my main method:

public static void main (String[] args) {
    //Testing the getPreviousNode method
    LinkedList myList = new LinkedList();

    myList.add(-700);
    myList.add("hello");
    myList.add(12);
    myList.add(55);
    myList.add(13000);
    myList.add("world");
    myList.add("pizza");
    myList.add(870);

    System.out.println("The previous node of the node containing 12 is the Node containing \"hello\":");

    System.out.println(myList.getPreviousNode(
         myList.getTop().getLink().getLink()).getData());
    System.out.println();

    //Testing swap:
    System.out.println("The initial list is:");
    System.out.println(myList);

    System.out.println();
    System.out.println("Now swapping the first and second nodes, and the result is:");
    myList.swap(myList.getTop(), myList.getTop().getLink());
    System.out.println(myList);
}