I am trying to learn how to print out a linked list. I have all the methods that I would need to use for the list, but I can't figure out how to display the values of the nodes. Right now there is nothing in my main method because I kept getting errors trying to call non-static methods in the main. I have a toString method that displays the contents of the list. How would I go about calling this toString to display the value of each node? Any advice will be greatly appreciated.

Here is the node class:

public class LinkedListNode 
{ 
    private int data; 
    private LinkedListNode next; 
    public LinkedListNode(int data) 
    { 
        this.data = data; 
        this.next = null; 
    } 
    public int getData() 
    { 
        return data; 
    } 
    public void setData(int d) 
    { 
        data = d; 
    } 
    public LinkedListNode getNext() 
    { 
        return next; 
    } 
    public void setNext(LinkedListNode n) 
    { 
        next = n; 
    } 
}

Here is the LinkedList class that contains  the main and methods to manipulate the list:

public class LinkedList { 
    public LinkedListNode head; 
    public static void main(String[] args) { 
    LinkedList l = new LinkedList(); 
    l.insertFront(0); 
    System.out.println(l.toString()); 
    } 
    public LinkedList() { 
        this.head = null; 
    } 
    public int removeFront(){ 
        if(head == null){ 
            System.out.println("Error - Attempting to call removeFront() on empty list"); 
            return 0; 
        }else{ 
            int temp = head.getData(); 
            head = head.getNext(); 
            return temp; 
        } 
    } 
    public void insertFront(int data){ 
        if(head == null){ 
            head = new LinkedListNode(data); 
        }else{ 
            LinkedListNode newNode = new LinkedListNode(data); 
            newNode.setNext(head); 
            head = newNode; 
        } 
    } 
    public void insertBack(int data){ 
        if(head == null){ 
            head = new LinkedListNode(data); 
        }else{ 
            LinkedListNode newNode = new LinkedListNode(data); 
            LinkedListNode current = head; 
            while(current.getNext() != null){ 
                current = current.getNext(); 
            } 
            current.setNext(newNode); 
        } 
    } 
    public int removeBack(){ 
        if(head == null){ 
            System.out.println("Error - Attempting to call removeBack() on empty list"); 
            return 0; 
        }else if (head.getNext() == null){ 
            int temp = head.getData(); 
            head = null; 
            return temp; 
        }else{ 
            LinkedListNode current = head; 
            while(current.getNext().getNext() != null){ 
                current = current.getNext(); 
            } 
            int temp = current.getNext().getData(); 
            current.setNext(null); 
            return temp; 
        } 
    } 
    public String toString(){ 
        String retStr = "Contents:\n"; 
        LinkedListNode current = head; 
        while(current != null){ 
            retStr += current.getData() + "\n"; 
            current = current.getNext(); 
        } 
        return retStr; 
    } 
    public LinkedListNode getHead() { 
        return head; 
    } 
    public void setHead(LinkedListNode head) { 
        this.head = head; 
    } 
}