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:

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1. package org.pbdevj.ds.search.binarysearchtree;
3. import java.io.Serializable;
5. /**树节点*/
6. public class TreeNodeimplements Serializable {
8. public Object nodeValue;//数据域
9. public TreeNode lChild;//左子树
10. public TreeNode rChild;//右子树
12. public TreeNode() {
13. // TODO Auto-generated constructor stub
14. }
16. public TreeNode(Object nodeValue, TreeNode lChild, TreeNode rChild) {
17. super();
18. this.nodeValue = nodeValue;
19. this.lChild = lChild;
20. this.rChild = rChild;
21. }
25. }

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:

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1. package org.pbdevj.ds.search.binarysearchtree;
3. /**查找回调接口*/
4. public interface ISearchCallBack {
6. void visit(TreeNode e);
8. }

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

查找接口：

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1. package org.pbdevj.ds.search.binarysearchtree;
3. /**查找接口*/
4. public interface ISearch {
6. TreeNode search(Object e);
8. TreeNode search(Object e,ISearchCallBack searchCallBack);
10. void output(ISearchCallBack searchCallBack);
12. }

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：

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1. package org.pbdevj.ds.search.binarysearchtree;
3. /**二叉查找树*/
4. public class BinarySearchTreeimplements ISearch {
6. private Object[] elements;
8. TreeNode rootNode;//树根节点
11. public BinarySearchTree(Object[] elements) {
12. // TODO Auto-generated constructor stub
13. this.elements = elements;
14. buildBinarySearchTree();
15. }
17. public BinarySearchTree(TreeNode rootNode) {
18. // TODO Auto-generated constructor stub
19. this.rootNode = rootNode;
20. }
22. /**构造二叉查找树*/
23. private void buildBinarySearchTree(){
24. if(elements==null || elements.length==0)
25. return;
27. rootNode =new TreeNode(elements[0],null,null);
28. if (elements.length==1)
29. return;
31. for (int index =1; index < elements.length; index++) {//每次循环从数组中取一个元素
32. TreeNode tempNode = rootNode;
33. 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
34. if (elements[index].toString().compareTo(tempNode.nodeValue.toString())<0){//小于中间节点
35. if (tempNode.lChild==null){
36. tempNode.lChild = new TreeNode(elements[index],null,null);
37. break;
38. }
39. tempNode = tempNode.lChild;//继续比较左子树
40. } else {
41. if (tempNode.rChild==null){
42. tempNode.rChild = new TreeNode(elements[index],null,null);
43. break;
44. }
45. tempNode = tempNode.rChild;//继续比较右子树
46. }
47. }
48. }
51. }
54. /**中序输出这个二叉查找树*/
55. @Override
56. public void output(ISearchCallBack searchCallBack) {
57. // TODO Auto-generated method stub
58. if (rootNode==null)
59. return;
61. _output(rootNode,searchCallBack);
62. }
64. /**中序输出这个二叉查找树[递归函数]*/
65. private void _output(TreeNode node,ISearchCallBack searchCallBack){
66. if (node.lChild!=null)//遍历左子树
67. _output(node.lChild,searchCallBack);
68. if (searchCallBack!=null)//访问根节点
69. searchCallBack.visit(node);
70. if (node.rChild!=null)//遍历右子树
71. _output(node.rChild,searchCallBack);
72. }
74. @Override
75. public TreeNode search(Object e) {
76. // TODO Auto-generated method stub
77. return null;
78. }
80. @Override
81. public TreeNode search(Object e, ISearchCallBack searchCallBack) {
82. // TODO Auto-generated method stub
83. return null;
84. }
86. }

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 stubthis.elements = elements;buildBinarySearchTree();}public BinarySearchTree(TreeNode rootNode) {// TODO Auto-generated constructor stubthis.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*/@Overridepublic void output(ISearchCallBack searchCallBack) {// TODO Auto-generated method stubif (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);}@Overridepublic TreeNode search(Object e) {// TODO Auto-generated method stubreturn null;}@Overridepublic TreeNode search(Object e, ISearchCallBack searchCallBack) {// TODO Auto-generated method stubreturn null;}}

单元测试:

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1. package org.pbdevj.ds.search.binarysearchtree.utest;
4. import org.junit.Before;
5. import org.junit.Test;
6. import org.pbdevj.ds.search.binarysearchtree.BinarySearchTree;
7. import org.pbdevj.ds.search.binarysearchtree.ISearch;
8. import org.pbdevj.ds.search.binarysearchtree.ISearchCallBack;
9. import org.pbdevj.ds.search.binarysearchtree.TreeNode;
11. public class BinarySearchTreeTest {
13. @Test
14. public void testOutput(){
15. ISearch search = new BinarySearchTree(new Object[]{
16. 50,30,10,20,60,90,70,45,43,32,38,44,21,20,55,65,67,76,77,88,77
17. });
18. search.output(new ISearchCallBack() {
20. @Override
21. public void visit(TreeNode e) {
22. // TODO Auto-generated method stub
23. System.out.println(e.nodeValue);
25. }
26. });
27. }
28. }