二叉查找树的构造与遍历[Java实现]

构造二叉查找树之插入算法：
比较新节点关键字与格子树根节点的大小关系。如果新节点关键字小，则递归进入相应根节点的左子树，直到找到左子树为空的位置；否则，递归进入相应根节点的右子树，直到找到右子树为空的位置。

树节点:

package org.pbdevj.ds.search.binarysearchtree;

import java.io.Serializable;

/**树节点*/
public class TreeNode implements Serializable {

public Object nodeValue;//数据域
public TreeNode lChild;//左子树
public TreeNode rChild;//右子树

public TreeNode() {
// TODO Auto-generated constructor stub
}

public TreeNode(Object nodeValue, TreeNode lChild, TreeNode rChild) {
super();
this.nodeValue = nodeValue;
this.lChild = lChild;
this.rChild = rChild;
}



}

package org.pbdevj.ds.search.binarysearchtree; import java.io.Serializable; /**树节点*/ public class TreeNode implements Serializable { public Object nodeValue;//数据域 public TreeNode lChild;//左子树 public TreeNode rChild;//右子树 public TreeNode() { // TODO Auto-generated constructor stub } public TreeNode(Object nodeValue, TreeNode lChild, TreeNode rChild) { super(); this.nodeValue = nodeValue; this.lChild = lChild; this.rChild = rChild; } }

查找回调接口:

package org.pbdevj.ds.search.binarysearchtree;

/**查找回调接口*/
public interface ISearchCallBack {

void visit(TreeNode e);

}

package org.pbdevj.ds.search.binarysearchtree; /**查找回调接口*/ public interface ISearchCallBack { void visit(TreeNode e); }

查找接口：

package org.pbdevj.ds.search.binarysearchtree;

/**查找接口*/
public interface ISearch {

TreeNode search(Object e);

TreeNode search(Object e,ISearchCallBack searchCallBack);

void output(ISearchCallBack searchCallBack);

}

package org.pbdevj.ds.search.binarysearchtree; /**查找接口*/ public interface ISearch { TreeNode search(Object e); TreeNode search(Object e,ISearchCallBack searchCallBack); void output(ISearchCallBack searchCallBack); }

二叉查找树：

package org.pbdevj.ds.search.binarysearchtree;

/**二叉查找树*/
public class BinarySearchTree implements ISearch {

private Object[] elements;

TreeNode rootNode;//树根节点


public BinarySearchTree(Object[] elements) {
// TODO Auto-generated constructor stub
this.elements = elements;
buildBinarySearchTree();
}

public BinarySearchTree(TreeNode rootNode) {
// TODO Auto-generated constructor stub
this.rootNode = rootNode;
}

/**构造二叉查找树*/
private void buildBinarySearchTree(){
if(elements==null || elements.length==0)
return;

rootNode =new TreeNode(elements[0],null,null);
if (elements.length==1)
return;

for (int index = 1; index < elements.length; index++) {//每次循环从数组中取一个元素
TreeNode tempNode = rootNode;
while(true){//将这个元素与左子树或右子树循环比较,小于则继续进入左子树的左子树，否则继续进入右子树的右子树
if (elements[index].toString().compareTo(tempNode.nodeValue.toString())<0){//小于中间节点
if (tempNode.lChild==null){
tempNode.lChild = new TreeNode(elements[index],null,null);
break;
}
tempNode = tempNode.lChild;//继续比较左子树
} else {
if (tempNode.rChild==null){
tempNode.rChild = new TreeNode(elements[index],null,null);
break;
}
tempNode = tempNode.rChild;//继续比较右子树
}
}
}


}


/**中序输出这个二叉查找树*/
@Override
public void output(ISearchCallBack searchCallBack) {
// TODO Auto-generated method stub
if (rootNode==null)
return;

_output(rootNode,searchCallBack);
}

/**中序输出这个二叉查找树[递归函数]*/
private void _output(TreeNode node,ISearchCallBack searchCallBack){
if (node.lChild!=null)//遍历左子树
_output(node.lChild,searchCallBack);
if (searchCallBack!=null)//访问根节点
searchCallBack.visit(node);
if (node.rChild!=null)//遍历右子树
_output(node.rChild,searchCallBack);
}

@Override
public TreeNode search(Object e) {
// TODO Auto-generated method stub
return null;
}

@Override
public TreeNode search(Object e, ISearchCallBack searchCallBack) {
// TODO Auto-generated method stub
return null;
}

}

package org.pbdevj.ds.search.binarysearchtree; /**二叉查找树*/ public class BinarySearchTree implements ISearch { private Object[] elements; TreeNode rootNode;//树根节点 public BinarySearchTree(Object[] elements) { // TODO Auto-generated constructor stub this.elements = elements; buildBinarySearchTree(); } public BinarySearchTree(TreeNode rootNode) { // TODO Auto-generated constructor stub this.rootNode = rootNode; } /**构造二叉查找树*/ private void buildBinarySearchTree(){ if(elements==null || elements.length==0) return; rootNode =new TreeNode(elements[0],null,null); if (elements.length==1) return; for (int index = 1; index < elements.length; index++) {//每次循环从数组中取一个元素 TreeNode tempNode = rootNode; while(true){//将这个元素与左子树或右子树循环比较,小于则继续进入左子树的左子树，否则继续进入右子树的右子树 if (elements[index].toString().compareTo(tempNode.nodeValue.toString())<0){//小于中间节点 if (tempNode.lChild==null){ tempNode.lChild = new TreeNode(elements[index],null,null); break; } tempNode = tempNode.lChild;//继续比较左子树 } else { if (tempNode.rChild==null){ tempNode.rChild = new TreeNode(elements[index],null,null); break; } tempNode = tempNode.rChild;//继续比较右子树 } } } } /**中序输出这个二叉查找树*/ @Override public void output(ISearchCallBack searchCallBack) { // TODO Auto-generated method stub if (rootNode==null) return; _output(rootNode,searchCallBack); } /**中序输出这个二叉查找树[递归函数]*/ private void _output(TreeNode node,ISearchCallBack searchCallBack){ if (node.lChild!=null)//遍历左子树 _output(node.lChild,searchCallBack); if (searchCallBack!=null)//访问根节点 searchCallBack.visit(node); if (node.rChild!=null)//遍历右子树 _output(node.rChild,searchCallBack); } @Override public TreeNode search(Object e) { // TODO Auto-generated method stub return null; } @Override public TreeNode search(Object e, ISearchCallBack searchCallBack) { // TODO Auto-generated method stub return null; } }

单元测试:

package org.pbdevj.ds.search.binarysearchtree.utest;


import org.junit.Before;
import org.junit.Test;
import org.pbdevj.ds.search.binarysearchtree.BinarySearchTree;
import org.pbdevj.ds.search.binarysearchtree.ISearch;
import org.pbdevj.ds.search.binarysearchtree.ISearchCallBack;
import org.pbdevj.ds.search.binarysearchtree.TreeNode;

public class BinarySearchTreeTest {

@Test
public void testOutput(){
ISearch search = new BinarySearchTree(new Object[]{
50,30,10,20,60,90,70,45,43,32,38,44,21,20,55,65,67,76,77,88,77
});
search.output(new ISearchCallBack() {

@Override
public void visit(TreeNode e) {
// TODO Auto-generated method stub
System.out.println(e.nodeValue);

}
});
}
}