Java：二叉树的递归遍历

class TreeNode{private Object data;public Object getData() {return data;}public void setData(Object data) {this.data = data;}TreeNode left=null;TreeNode right=null;}public class order {//先序遍历public void PreOrder(TreeNode root) {if(root!=null) {System.out.print(root.getData());PreOrder(root.left);PreOrder(root.right);}}//中序遍历public void InOrder(TreeNode root) {if(root!=null) {PreOrder(root.left);System.out.print(root.getData());PreOrder(root.right);}}//后序遍历public void PostOrder(TreeNode root) {if(root!=null) {PostOrder(root.left);PostOrder(root.right);System.out.print(root.getData());}}}