二叉树前序遍历非递归实现

public static void qian1(Node node) {Stack< Node > s= new Stack<>();while (node!=null || !s.isEmpty()) {if(node!= null) {System.out.print(node.getData());s.push(node);node = node.getlNode();}else {node = s.pop();node = node.getrNode();}}System.out.println();}