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java代码如何写树 java编写
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用java怎么构造一个二叉树？
二叉树的相关操作，包括创建，中序、先序、后序（递归和非递归），其中重点的是java在先序创建二叉树和后序非递归遍历的的实现。
package com.algorithm.tree;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Queue;
import java.util.Scanner;
import java.util.Stack;
import java.util.concurrent.LinkedBlockingQueue;
public class Tree {
private Node root;
public Tree() {
}
public Tree(Node root) {
this.root = root;
}
//创建二叉树
public void buildTree() {
Scanner scn = null;
try {
scn = new Scanner(new File("input.txt"));
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
root = createTree(root,scn);
}
//先序遍历创建二叉树
private Node createTree(Node node,Scanner scn) {
String temp = scn.next();
if (temp.trim().equals("#")) {
return null;
} else {
node = new Node((T)temp);
node.setLeft(createTree(node.getLeft(), scn));
node.setRight(createTree(node.getRight(), scn));
return node;
}
}
//中序遍历(递归)
public void inOrderTraverse() {
inOrderTraverse(root);
}
public void inOrderTraverse(Node node) {
if (node != null) {
inOrderTraverse(node.getLeft());
System.out.println(node.getValue());
inOrderTraverse(node.getRight());
}
}
//中序遍历(非递归)
public void nrInOrderTraverse() {
StackNode stack = new StackNode();
Node node = root;
while (node != null || !stack.isEmpty()) {
while (node != null) {
stack.push(node);
node = node.getLeft();
}
node = stack.pop();
System.out.println(node.getValue());
node = node.getRight();
}
}
//先序遍历(递归)
public void preOrderTraverse() {
preOrderTraverse(root);
}
public void preOrderTraverse(Node node) {
if (node != null) {
System.out.println(node.getValue());
preOrderTraverse(node.getLeft());
preOrderTraverse(node.getRight());
}
}
//先序遍历（非递归）
public void nrPreOrderTraverse() {
StackNode stack = new StackNode();
Node node = root;
while (node != null || !stack.isEmpty()) {
while (node != null) {
System.out.println(node.getValue());
stack.push(node);
node = node.getLeft();
}
node = stack.pop();
node = node.getRight();
}
}
//后序遍历(递归)
public void postOrderTraverse() {
postOrderTraverse(root);
}
public void postOrderTraverse(Node node) {
if (node != null) {
postOrderTraverse(node.getLeft());
postOrderTraverse(node.getRight());
System.out.println(node.getValue());
}
}
//后续遍历(非递归)
public void nrPostOrderTraverse() {
StackNode stack = new StackNode();
Node node = root;
Node preNode = null;//表示最近一次访问的节点
while (node != null || !stack.isEmpty()) {
while (node != null) {
stack.push(node);
node = node.getLeft();
}
node = stack.peek();
if (node.getRight() == null || node.getRight() == preNode) {
System.out.println(node.getValue());
node = stack.pop();
preNode = node;
node = null;
} else {
node = node.getRight();
}
}
}
//按层次遍历
public void levelTraverse() {
levelTraverse(root);
}
public void levelTraverse(Node node) {
QueueNode queue = new LinkedBlockingQueueNode();
queue.add(node);
while (!queue.isEmpty()) {
Node temp = queue.poll();
if (temp != null) {
System.out.println(temp.getValue());
queue.add(temp.getLeft());
queue.add(temp.getRight());
}
}
}
}
//树的节点
class Node {
private Node left;
private Node right;
private T value;
public Node() {
}
public Node(Node left,Node right,T value) {
this.left = left;
this.right = right;
this.value = value;
}
public Node(T value) {
this(null,null,value);
}
public Node getLeft() {
return left;
}
public void setLeft(Node left) {
this.left = left;
}
public Node getRight() {
return right;
}
public void setRight(Node right) {
this.right = right;
}
public T getValue() {
return value;
}
public void setValue(T value) {
this.value = value;
}
}
测试代码：
package com.algorithm.tree;
public class TreeTest {
/**
* @param args
*/
public static void main(String[] args) {
Tree tree = new Tree();
tree.buildTree();
System.out.println("中序遍历");
tree.inOrderTraverse();
tree.nrInOrderTraverse();
System.out.println("后续遍历");
//tree.nrPostOrderTraverse();
tree.postOrderTraverse();
tree.nrPostOrderTraverse();
System.out.println("先序遍历");
tree.preOrderTraverse();
tree.nrPreOrderTraverse();
//
}
}
相关问答
Q1: java中如何建立一个java树，请详解？
import java.awt.*;
import javax.swing.*;
class TreeDemo extends JFrame
{
public TreeDemo()
{
setSize(400,300);
setTitle("演示怎样使用JTree");
show();
JScrollPane jPanel=new JScrollPane();
getContentPane().add(jPanel);
JTree jtree=new JTree();
jPanel.getViewport().add(jtree,null);
validate();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
public class Example5_25
{
public static void main(String[] args)
{
TreeDemo frame=new TreeDemo();
}
}
其中JScrollPane是一个带滚动条java代码如何写树的面板类。
将对象加入到带滚动条java代码如何写树的面板类中java代码如何写树，在将已建java代码如何写树的数放入到其中。
就可建立一个系统默认java代码如何写树的树结构。
Q2: 用java怎么构造一个二叉树呢？
java构造二叉树，可以通过链表来构造，如下代码：
public class BinTree {
public final static int MAX=40;
BinTree []elements = new BinTree[MAX];//层次遍历时保存各个节点
int front;//层次遍历时队首
int rear;//层次遍历时队尾
private Object data; //数据元数
private BinTree left,right; //指向左,右孩子结点的链
public BinTree()
{
}
public BinTree(Object data)
{ //构造有值结点
this.data = data;
left = right = null;
}
public BinTree(Object data,BinTree left,BinTree right)
{ //构造有值结点
this.data = data;
this.left = left;
this.right = right;
}
public String toString()
{
return data.toString();
}
//前序遍历二叉树
public static void preOrder(BinTree parent){
if(parent == null)
return;
System.out.print(parent.data+" ");
preOrder(parent.left);
preOrder(parent.right);
}
//中序遍历二叉树
public void inOrder(BinTree parent){
if(parent == null)
return;
inOrder(parent.left);
System.out.print(parent.data+" ");
inOrder(parent.right);
}
//后序遍历二叉树
public void postOrder(BinTree parent){
if(parent == null)
return;
postOrder(parent.left);
postOrder(parent.right);
System.out.print(parent.data+" ");
}
// 层次遍历二叉树
public void LayerOrder(BinTree parent)
{
elements[0]=parent;
front=0;rear=1;
while(frontrear)
{
try
{
if(elements[front].data!=null)
{
System.out.print(elements[front].data + " ");
if(elements[front].left!=null)
elements[rear++]=elements[front].left;
if(elements[front].right!=null)
elements[rear++]=elements[front].right;
front++;
}
}catch(Exception e){break;}
}
}
//返回树的叶节点个数
public int leaves()
{
if(this == null)
return 0;
if(left == nullright == null)
return 1;
return (left == null ? 0 : left.leaves())+(right == null ? 0 : right.leaves());
}
//结果返回树的高度
public int height()
{
int heightOfTree;
if(this == null)
return -1;
int leftHeight = (left == null ? 0 : left.height());
int rightHeight = (right == null ? 0 : right.height());
heightOfTree = leftHeightrightHeight?rightHeight:leftHeight;
return 1 + heightOfTree;
}
//如果对象不在树中,结果返回-1;否则结果返回该对象在树中所处的层次,规定根节点为第一层
public int level(Object object)
{
int levelInTree;
if(this == null)
return -1;
if(object == data)
return 1;//规定根节点为第一层
int leftLevel = (left == null?-1:left.level(object));
int rightLevel = (right == null?-1:right.level(object));
if(leftLevel0rightLevel0)
return -1;
levelInTree = leftLevelrightLevel?rightLevel:leftLevel;
return 1+levelInTree;
}
//将树中的每个节点的孩子对换位置
public void reflect()
{
if(this == null)
return;
if(left != null)
left.reflect();
if(right != null)
right.reflect();
BinTree temp = left;
left = right;
right = temp;
}
// 将树中的所有节点移走,并输出移走的节点
public void defoliate()
{
if(this == null)
return;
//若本节点是叶节点，则将其移走
if(left==nullright == null)
{
System.out.print(this + " ");
data = null;
return;
}
//移走左子树若其存在
if(left!=null){
left.defoliate();
left = null;
}
//移走本节点，放在中间表示中跟移走...
String innerNode += this + " ";
data = null;
//移走右子树若其存在
if(right!=null){
right.defoliate();
right = null;
}
}
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
BinTree e = new BinTree("E");
BinTree g = new BinTree("G");
BinTree h = new BinTree("H");
BinTree i = new BinTree("I");
BinTree d = new BinTree("D",null,g);
BinTree f = new BinTree("F",h,i);
BinTree b = new BinTree("B",d,e);
BinTree c = new BinTree("C",f,null);
BinTree tree = new BinTree("A",b,c);
System.out.println("前序遍历二叉树结果: ");
tree.preOrder(tree);
System.out.println();
System.out.println("中序遍历二叉树结果: ");
tree.inOrder(tree);
System.out.println();
System.out.println("后序遍历二叉树结果: ");
tree.postOrder(tree);
System.out.println();
System.out.println("层次遍历二叉树结果: ");
tree.LayerOrder(tree);
System.out.println();
System.out.println("F所在的层次: "+tree.level("F"));
System.out.println("这棵二叉树的高度: "+tree.height());
System.out.println("--------------------------------------");
tree.reflect();
System.out.println("交换每个节点的孩子节点后......");
System.out.println("前序遍历二叉树结果: ");
tree.preOrder(tree);
System.out.println();
System.out.println("中序遍历二叉树结果: ");
tree.inOrder(tree);
System.out.println();
System.out.println("后序遍历二叉树结果: ");
tree.postOrder(tree);
System.out.println();
System.out.println("层次遍历二叉树结果: ");
tree.LayerOrder(tree);
System.out.println();
System.out.println("F所在的层次: "+tree.level("F"));
System.out.println("这棵二叉树的高度: "+tree.height());
}
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