// @author Frank M. Carrano, Timothy M. Henry
// @version 5.0
private void initializeTree(T rootData, BinaryTree<T> leftTree, BinaryTree<T> rightTree)
{
   root = new BinaryNode<>(rootData);

   if ((leftTree != null) && !leftTree.isEmpty())
      root.setLeftChild(leftTree.root);

   if ((rightTree != null) && !rightTree.isEmpty())
   {
      if (rightTree != leftTree)
         root.setRightChild(rightTree.root);
      else
         root.setRightChild(rightTree.root.copy());
   } // end if

   if ((leftTree != null) && (leftTree != this))
      leftTree.clear();

   if ((rightTree != null) && (rightTree != this))
      rightTree.clear();
} // end initializeTree