二叉树遍历前序遍历

public void  preOrderTraverse(TreeNode node){
   Statck<TreeNode>  nodes=new Statck<>();
   nodes.push(node);
   while(!nodes.isEmpty())
   {
TreeNode current=nodes.pop();
visitNode(current);
        if(current.right!=null)
     ndoes.push(current.right);
 if(current.left!=null)
     ndoes.push(current.left);
   }
}