java编写二叉树以及前序遍历、中序遍历和后序遍历

/**
* 实现二叉树的创建、前序遍历、中序遍历和后序遍历
**/
package DataStructure;

/**
* Copyright 2014 by Ruiqin Sun
* All right reserved
* created  on 2014-9-9 下午2:34:15
**/
public class BinTreeInt {
private Node root;

/**
* 创建内部节点类
**/
private class Node{
//		左节点
private Node leftChild;
//		右节点
private Node rightChild;
//		节点对应的值
private int data;

public Node(int data){
this.leftChild = null;
this.rightChild = null;
this.data = data;
}
}// class Node

public BinTreeInt(){
root = null;
}

/*
*递归的创建二叉树
* */
public void buildTree(Node node ,int data){
if (root == null){// 如果根节点为空，创建根节点
root = new Node(data);
}else{
if(data <node.data){//插入到左子树
if(node.leftChild == null){//左节点为空，直接创建值为data的左节点
node.leftChild = new Node(data);
}else{//左节点不为空，调用buildTree函数插到左子树中
buildTree(node.leftChild,data);
}
}else{
if(node.rightChild == null){
node.rightChild = new Node(data);
}else{
buildTree(node.rightChild,data);
}
}
}
}//end buildTree
/*
*前序遍历二叉树
* */
public void preOrder(Node node){
if(node != null){
System.out.print(node.data);
preOrder(node.leftChild);
preOrder(node.rightChild);
}
}
/*
*中序遍历二叉树
* */
public void inOrder(Node node){
if(node != null){
inOrder(node.leftChild);
System.out.print(node.data);
inOrder(node.rightChild);
}
}
/*
*后序遍历二叉树
* */
public void postOrder(Node node){
if(node != null){
postOrder(node.leftChild);
postOrder(node.rightChild);
System.out.print(node.data);
}
}

public static void main(String ars[]){
int[] a={2,4,12,45,21,6,111};
BinTreeInt binTree = new BinTreeInt();
for(int i = 0; i<a.length; i++){
binTree.buildTree(binTree.root, a[i]);
}
System.out.print("前序遍历");
binTree.preOrder(binTree.root);
System.out.println("");
System.out.print("中序遍历");
binTree.inOrder(binTree.root);
System.out.println("");
System.out.print("后序遍历");
binTree.postOrder(binTree.root);
}
}