Evaluating the code of your implementation TreeSet

Given the task to create your own implementation of a TreeSet , which should have the add(E e) and List<E> get() methods.

Does my code correctly illustrate the operation of a TreeSet ? If it is incorrect, then in what?

If it is at least partially correct, then how can I test that I created the tree, because my get method according to the condition of the problem returns a List ?

Implemented interface:

 public interface Tree<E> extends Iterable<E> { boolean add(E e); List<E> get(); int size(); } 

The implementation itself:

 public class SimpleTreeSet<E> implements Tree<E> { private Leaf<E> root; private List<E> list; private int size = 0; public SimpleTreeSet() { list = new LinkedList<>(); } @Override public boolean add(E e) { if (size == 0) { return initRootLeaf(e); } Leaf<E> newNode = new Leaf<>(e); Leaf<E> lastNode = findLastLeaf(root, newNode); if (lastNode == null) { return false; } // храню элементы для итератора и get list.add(newNode.element); if (lastNode.compareTo(newNode) > 0) { lastNode.right = newNode; size++; return true; } else { lastNode.left = newNode; size++; return true; } } // ищу последний лист дерева private Leaf<E> findLastLeaf( final Leaf<E> oldLeaf, final Leaf<E> newLeaf ) { Leaf<E> lastLeaf = oldLeaf; int compare = oldLeaf.compareTo(newLeaf); if (compare > 0 && oldLeaf.right != null) { lastLeaf = findLastLeaf(oldLeaf.right, newLeaf); return lastLeaf; } if (compare < 0 && oldLeaf.left != null) { lastLeaf = findLastLeaf(oldLeaf.left, newLeaf); return lastLeaf; } if (compare == 0) return null; return lastLeaf; } private boolean initRootLeaf(final E e) { root = new Leaf<>(e); list.add(e); size++; return true; } @Override public List<E> get() { return list; } @Override public int size() { return size; } @Override public Iterator<E> iterator() { return list.iterator(); } private class Leaf<E> implements Comparable<E> { private Leaf<E> right; private Leaf<E> left; private E element; private Leaf(E element) { this.element = element; } @Override public int compareTo(Object obj) { if (obj instanceof SimpleTreeSet.Leaf) { Leaf<E> node = (Leaf<E>) obj; return this.hashCode() - node.hashCode(); } throw new ClassCastException(); } @Override public int hashCode() { int hash = 31; hash = hash * 17 + element.hashCode(); return hash; } } }