LinkedList.java

public class LinkedList implements List {

    private Node head;

    public void add(Object o) {

    }

    public void add(int index, Object o) {

    }

    public Object get(int index) {
        return null;
    }

    public Object remove(int index) {
        return null;
    }

    public int size() {
        return -1;
    }

    public void addFirst(Object o) {

    }

    public void addLast(Object o) {

    }

    public Object removeFirst() {
        return null;
    }

    public Object removeLast() {
        return null;
    }

    public Iterator iterator() {
        return null;
    }


    private static class Node {
        Object data;
        Node next;

    }
}