java数据结构与算法二叉树实验代码没有报错，但是输出结果总是不对输出结果是：先根遍历：aexperiment2_BiTree.BiTreeNode@c9d92cexperiment2_BiTree.BiTreeNode@1d0fafc中根遍历：experiment2_BiTree.BiTreeNode@c9d92caexperiment2_BiTree.BiTreeNode@1d0fafc后根遍历：experiment2_BiTree.BiTreeNode@c9d92cexperiment2_BiTree.BiTreeNode@1d0fafca