Someone

public void insertThreaded(E x)
	{
		if (root==null)
		{
			root = new ThreadedTreeNode<E>(x);
		}
		current = root;
		//
		//find appropriate null node to insert new node
		while(current.getData()!= null)
		{
			//initialize trailer to current
			trailer = current;
			//if x > current.data, move to right subtree
			if (x.compareTo(current.getData())>0)
			{
				trailer = current;
				current = current.getRight();
			}
			//if x < current.data, move to left subtree
			else if (x.compareTo(current.getData())<0)
			{
				trailer = current;
				current = current.getLeft();
			}
			//break loop if node x already exist in tree.
			else
			{
				break;
			}
		}
		//
		//current is null, compare x with trailer.data and insert x as child to trailer.
		//if x > trailer.data, move to right subtree
		if (x.compareTo(trailer.getData())>0)
		{
			//create new node for x with null left reference and right thread from trailer
			ThreadedTreeNode<E> node = new ThreadedTreeNode<E>(x, null, trailer.getRight());
			//set trailer right reference to x
			trailer.setRight(node);
			//remove isThread flag from trailer
			trailer.setIsThread(false);
			
		}
		//if x < trailer.data, move to left subtree
		else if(x.compareTo(trailer.getData())<0)
		{
			//create new node for x with null left reference and right thread from trailer
			ThreadedTreeNode<E> node = new ThreadedTreeNode<E>(x, null, trailer.getRight());
			//set trailer left reference to x
			trailer.setLeft(node);
			//remove isThread flag from trailer
			trailer.setIsThread(false);
		}
		//do nothing if node x already exists in tree
		else
		{	
		}
	}