public class List<T> implements IList<T> { private class Node { private T item; private Node next; public Node(T item, Node next) { this.item = item; this.next = next; } public Node(T item) { this.item = item; this.next = null; } } private Node root; public void addAt(int pos, T elem) { if (root == null) { root = new Node(elem); } else if (pos == 0) { root = new Node(elem, root); } else if (pos > 0) { Node walker = root; Node prev = null; while (walker != null && pos > 0) { pos--; prev = walker; walker = walker.next; } walker = new Node(elem, walker); prev.next = walker; } } public boolean removeAt(int pos) { return false; } public int find(T elem) { int returnValue = 0; Node walker = root; while (walker != null && walker.item != elem) { walker = walker.next; returnValue++; } if (walker == null) { returnValue = -1; } return returnValue; } public int size() { int returnValue = 0; Node walker = root; while (walker != null) { walker = walker.next; returnValue++; } return returnValue; } public void clear() { } public void append(IList<T> aList) { } public String[] getAllElementsAsStrings() { int size = size(); String[] list = new String[size]; Node walker = root; for (int i = 0; i < size; ++i) { list[i] = (String)walker.item; walker = walker.next; } return list; } }