⑴ java实现二叉树层次遍历
import java.util.ArrayList;
public class TreeNode {
private TreeNode leftNode;
private TreeNode rightNode;
private String nodeName;
public TreeNode getLeftNode() {
return leftNode;
}
public void setLeftNode(TreeNode leftNode) {
this.leftNode = leftNode;
}
public TreeNode getRightNode() {
return rightNode;
}
public void setRightNode(TreeNode rightNode) {
this.rightNode = rightNode;
}
public String getNodeName() {
return nodeName;
}
public void setNodeName(String nodeName) {
this.nodeName = nodeName;
}
public static int level=0;
public static void findNodeByLevel(ArrayList<TreeNode> nodes){
if(nodes==null||nodes.size()==0){
return ;
}
level++;
ArrayList<TreeNode> temp = new ArrayList();
for(TreeNode node:nodes){
System.out.println("第"+level+"层:"+node.getNodeName());
if(node.getLeftNode()!=null){
temp.add(node.getLeftNode());
}
if(node.getRightNode()!=null){
temp.add(node.getRightNode());
}
}
nodes.removeAll(nodes);
findNodeByLevel(temp);
}
/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
TreeNode root = new TreeNode();
root.setNodeName("root");
TreeNode node1 = new TreeNode();
node1.setNodeName("node1");
TreeNode node3 = new TreeNode();
node3.setNodeName("node3");
TreeNode node7 = new TreeNode();
node7.setNodeName("node7");
TreeNode node8 = new TreeNode();
node8.setNodeName("node8");
TreeNode node4 = new TreeNode();
node4.setNodeName("node4");
TreeNode node2 = new TreeNode();
node2.setNodeName("node2");
TreeNode node5 = new TreeNode();
node5.setNodeName("node5");
TreeNode node6 = new TreeNode();
node6.setNodeName("node6");
root.setLeftNode(node1);
node1.setLeftNode(node3);
node3.setLeftNode(node7);
node3.setRightNode(node8);
node1.setRightNode(node4);
root.setRightNode(node2);
node2.setLeftNode(node5);
node2.setRightNode(node6);
ArrayList<TreeNode> nodes = new ArrayList<TreeNode>();
nodes.add(root);
findNodeByLevel(nodes);
}
}
⑵ java 由字符串构成的二叉树
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(front<rear) { 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 == null&&right == 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 = leftHeight<rightHeight?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(leftLevel<0&&rightLevel<0) return -1; levelInTree = leftLevel<rightLevel?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==null&&right == 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());
⑶ Java循环遍历什么意思
比如
for (int i = 0; i < 10; i++) {System.out.println(i);}
就是循环遍历
出0-9
下面说得具体点
循环语句使语句或块的执行得以重复进行。Java 编程语言支持三种循环构造类型：for，while 和 do 循环。for 和 while 循环是在执行循环体之前测试循环条件，而 do 循环是在执行完循环体之后测试循环条件。这就意味着 for 和 while 循环可能连一次循环体都未执行，而 do 循环将至少执行一次循环体。
【1】 for 循环
for 循环的句法是：
for (初值表达式; boolean 测试表达式; 改变量表达式)｛
语句或语句块
｝
注意：for 语句里面的 3 个部分都可以省略，但是我们不建议这么做。
【2】 while 循环
while 循环的句法是：
while (布尔表达式) ｛
语句或块
｝
请确认循环控制变量在循环体被开始执行之前已被正确初始化，并确认循环控制变量是真时，循环体才开始执行。控制变量必须被正确更新以防止死循环。
【3】do while循环
do while循环的句法是：
do ｛
语句或块；
｝while (布尔测试);
象 while 循环一样，请确认循环控制变量在循环体中被正确初始化和测试并被适时更新。作为一种编程惯例，for 循环一般用在那种循环次数事先可确定的情况，而 while 和 do用在那种循环次数事先不可确定的情况。
do 循环与 while 循环的不同这处在于，前者至少执行一次，而后者可能一次都不执行。
【4】 特殊循环流程控制
下列语句可被用在更深层次的控制循环语句中：
break；
continue；
break 语句被用来从 switch 语句、循环语句中退出，跳出离 break 最近的循环。
continue 语句被用来略过并跳到循环体的结尾，终止本次循环，继续下一次循环。
⑷ 怎样使用java对二叉树进行层次遍历
publicclassBinaryTree{
intdata;//根节点数据
BinaryTreeleft;//左子树
BinaryTreeright;//右子树
publicBinaryTree(intdata)//实例化二叉树类
{
this.data=data;
left=null;
right=null;
}
publicvoidinsert(BinaryTreeroot,intdata){//向二叉树中插入子节点
if(data>root.data)//二叉树的左节点都比根节点小
{
if(root.right==null){
root.right=newBinaryTree(data);
}else{
this.insert(root.right,data);
}
}else{//二叉树的右节点都比根节点大
if(root.left==null){
root.left=newBinaryTree(data);
}else{
this.insert(root.left,data);
}
}
}
}
当建立好二叉树类后可以创建二叉树实例，并实现二叉树的先根遍历，中根遍历，后根遍历，代码如下：
packagepackage2;
publicclassBinaryTreePreorder{
publicstaticvoidpreOrder(BinaryTreeroot){//先根遍历
if(root!=null){
System.out.print(root.data+"-");
preOrder(root.left);
preOrder(root.right);
}
}
publicstaticvoidinOrder(BinaryTreeroot){//中根遍历
if(root!=null){
inOrder(root.left);
System.out.print(root.data+"--");
inOrder(root.right);
}
}
publicstaticvoidpostOrder(BinaryTreeroot){//后根遍历
if(root!=null){
postOrder(root.left);
postOrder(root.right);
System.out.print(root.data+"---");
}
}
publicstaticvoidmain(String[]str){
int[]array={12,76,35,22,16,48,90,46,9,40};
BinaryTreeroot=newBinaryTree(array[0]);//创建二叉树
for(inti=1;i<array.length;i++){
root.insert(root,array[i]);//向二叉树中插入数据
}
System.out.println("先根遍历：");
preOrder(root);
System.out.println();
System.out.println("中根遍历：");
inOrder(root);
System.out.println();
System.out.println("后根遍历：");
postOrder(root);
⑸ java层次遍历算法思路
找个例子看一下就有了。比如递归前序遍历二叉树，即先根遍历。先遍历根节点，之后向下又是一个跟节点，在遍历做节点，在遍历右节点，依次下去，知道没有右节点结束。在遍历右边的部分，根节点，左节点，右节点，知道没有右节点是为止。至此遍历结束。书上有图一看就知道了。其他的遍历按照遍历算法一样。建议看下数据结构的遍历，讲的很详细。
⑹ 用java怎么构造一个二叉树
定义一个结点类：
public class Node {
private int value;
private Node leftNode;
private Node rightNode;
public Node getRightNode() {
return rightNode;
}
public void setRightNode(Node rightNode) {
this.rightNode = rightNode;
}
public int getValue() {
return value;
}
public void setValue(int value) {
this.value = value;
}
public Node getLeftNode() {
return leftNode;
}
public void setLeftNode(Node leftNode) {
this.leftNode = leftNode;
}
}
初始化结点树：
public void initNodeTree()
{
int nodeNumber;
HashMap<String, Integer> map = new HashMap<String, Integer>();
Node nodeTree = new Node();
Scanner reader = new Scanner(System.in);
nodeNumber = reader.nextInt();
for(int i = 0; i < nodeNumber; i++) {
int value = reader.nextInt();
String str = reader.next();
map.put(str, value);
}
if (map.containsKey("#")) {
int value = map.get("#");
nodeTree.setValue(value);
setChildNode(map, value, nodeTree);
}
preTraversal(nodeTree);
}
private void setChildNode(HashMap<String, Integer> map, int nodeValue, Node parentNode) {
int value = 0;
if (map.containsKey("L" + nodeValue)) {
value = map.get("L" + nodeValue);
Node leftNode = new Node();
leftNode.setValue(value);
parentNode.setLeftNode(leftNode);
setChildNode(map, value, leftNode);
}
if (map.containsKey("R" + nodeValue)) {
value = map.get("R" + nodeValue);
Node rightNode = new Node();
rightNode.setValue(value);
parentNode.setRightNode(rightNode);
setChildNode(map, value, rightNode);
}
}
前序遍历该结点树：
public void preTraversal(Node nodeTree) {
if (nodeTree != null) {
System.out.print(nodeTree.getValue() + "\t");
preTraversal(nodeTree.getLeftNode());
preTraversal(nodeTree.getRightNode());
}
}
⑺ java网状结构怎么遍历
在构建框架时,需要考虑的是展示的逻辑组织以及它的内容,它们如何才能够和网页上能够看到的一些通常的组织结构相匹配,以下是几种逻辑组织.
1.布告板,一个单独的简单的网页,它通常描述一个人,小的业务或者简单的产品,大多数的个人网站都是这种类型,它们通常包含一些链接,这些链接是指向网络上的相关资源的,但是不能向相同文档内的任何其他网页.
2.单页线性,一个网页或长或短,它被设计成从头到尾地进行阅读,通常使用一些规则将这样一个网页分解成虚拟的页,读者可以翻阅整个网页,但是也可以使用内容和目标的表格来快速跳至任何部分,这种类型最适合于比较短的文档,而且这个文档中所有的信息很自然地从头到尾过渡.
3.多页线性,和单页线性的基本思想相同,但是它被分解成多个逻辑上连续的,一个接一个的网页,从开头到结束,就像一管委会故事一样,通过旋转在每一页底部的一个指向下一页的链接来引导读者遍历整个系列的网页.
4.分层,典型的网站结构,一个首页,包含到其他网页的链接,每一页包含一个主要的主题区,每一个这样的网页又可以包含指向更多网页的多个链接,将主题分解,这样的结果但是一个树型的结构.
5.网状,一个网状的结构是一个没有层次的分级的结构,这样的文档中有多个网页,而在其中的任意一个网页又都包含有连接到其他网页的链接,可能会有一个有页,但是从那里进入之后,读者就可以在此网中来来去去,且不须沿一个特定的路径,网状的结构是松散并且自由游走的,最适宜于娱乐,休闲的主题,或者那些难于进行顺序或层次分解的主题.
⑻ java 实现二叉树的层次遍历
class TreeNode {
public TreeNode left;
public TreeNode right;
public int value;
public TreeNode(TreeNode left, TreeNode right, int value) {
this.left = left;
this.right = right;
this.value = value;
}
}
public class BinaryTree {
public static int getTreeHeight(TreeNode root) {
if (root == null)
return 0;
if (root.left == null && root.right == null)
return 1;
return 1 + Math
.max(getTreeHeight(root.left), getTreeHeight(root.right));
}
public static void recursePreOrder(TreeNode root) {
if (root == null)
return;
System.out.println(root.value);
if (root.left != null)
recursePreOrder(root.left);
if (root.right != null)
recursePreOrder(root.right);
}
public static void stackPreOrder(TreeNode root) {
Stack stack = new Stack();
if (root == null)
return;
stack.push(root);
System.out.println(root.value);
TreeNode temp = root.left;
while (temp != null) {
stack.push(temp);
System.out.println(temp.value);
temp = temp.left;
}
temp = (TreeNode) stack.pop();
while (temp != null) {
temp = temp.right;
while (temp != null) {
stack.push(temp);
System.out.println(temp.value);
temp = temp.left;
}
if (stack.empty())
break;
temp = (TreeNode) stack.pop();
}
}
public static void recurseInOrder(TreeNode root) {
if (root == null)
return;
if (root.left != null)
recurseInOrder(root.left);
System.out.println(root.value);
if (root.right != null)
recurseInOrder(root.right);
}
public static void stackInOrder(TreeNode root) {
Stack stack = new Stack();
if (root == null)
return;
else
stack.push(root);
TreeNode temp = root.left;
while (temp != null) {
stack.push(temp);
temp = temp.left;
}
temp = (TreeNode) stack.pop();
while (temp != null) {
System.out.println(temp.value);
temp = temp.right;
while (temp != null) {
stack.push(temp);
temp = temp.left;
}
if (stack.empty())
break;
temp = (TreeNode) stack.pop();
}
}
public static void main(String[] args) {
TreeNode node1 = new TreeNode(null, null, 1);
TreeNode node2 = new TreeNode(null, node1, 2);
TreeNode node3 = new TreeNode(null, null, 3);
TreeNode node4 = new TreeNode(node2, node3, 4);
TreeNode node5 = new TreeNode(null, null, 5);
TreeNode root = new TreeNode(node4, node5, 0);
System.out.println("Tree Height is " + getTreeHeight(root));
System.out.println("Recurse In Order Traverse");
recurseInOrder(root);
System.out.println("Stack In Order Traverse");
stackInOrder(root);
System.out.println("Recurse Pre Order Traverse");
recursePreOrder(root);
System.out.println("Stack Pre Order Traverse");
stackPreOrder(root);
}
}
可以做个参考
⑼ 写一个java层次遍历二叉树,简单点就可以,我要的是代码,不是纯文字说明
public class BinaryNode {
Object element;
BinaryNode left;
BinaryNode right;
}
import java.util.*;
public class Queue {
protected LinkedList list;
// Postcondition: this Queue object has been initialized.
public Queue() {
list = new LinkedList();
} // default constructor
// Postcondition: the number of elements in this Queue object has been
// returned.
public int size() {
return list.size();
} // method size
// Postcondition: true has been returned if this Queue object has no
// elements. Otherwise, false has been returned.
public boolean isEmpty() {
return list.isEmpty();
} // method isEmpty
// Postconditon: A of element has been inserted at the back of this
// Queue object. The averageTime (n) is constant and
// worstTime (n) is O (n).
public void enqueue(Object element) {
list.addLast(element);
} // method enqueue
// Precondition: this Queue object is not empty. Otherwise,
// NoSuchElementException will be thrown.
// Postcondition: The element that was at the front of this Queue object -
// just before this method was called -- has been removed
// from this Queue object and returned.
public Object dequeue() {
return list.removeFirst();
} // method dequeue
// Precondition: this Queue object is not empty. Otherwise,
// NoSuchElementException will be thrown.
// Postcondition: the element at index 0 in this Queue object has been
// returned.
public Object front() {
return list.getFirst();
} // method front
} // Queue class
import java.io.IOException;
public class BinaryTree {
BinaryNode root;
public BinaryTree() {
super();
// TODO 自动生成构造函数存根
root=this.createPre();
}
public BinaryNode createPre()
//按照先序遍历的输入方法，建立二叉树
{
BinaryNode t=null;
char ch;
try {
ch = (char)System.in.read();
if(ch==' ')
t=null;
else
{
t=new BinaryNode();
t.element=(Object)ch;
t.left=createPre();
t.right=createPre();
}
} catch (IOException e) {
// TODO 自动生成 catch 块
e.printStackTrace();
}
return t;
}
public void inOrder()
{
this.inOrder(root);
}
public void inOrder(BinaryNode t)
//中序遍历二叉树
{
if(t!=null)
{
inOrder(t.left);
System.out.print(t.element);
inOrder(t.right);
}
}
public void postOrder()
{
this.postOrder(root);
}
public void postOrder(BinaryNode t)
//后序遍历二叉树
{
if(t!=null)
{
postOrder(t.left);
System.out.print(t.element);
postOrder(t.right);
}
}
public void preOrder()
{
this.preOrder(root);
}
public void preOrder(BinaryNode t)
//前序遍历二叉树
{
if(t!=null)
{
System.out.print(t.element);
preOrder(t.left);
preOrder(t.right);
}
}
public void breadthFirst()
{
Queue treeQueue=new Queue();
BinaryNode p;
if(root!=null)
treeQueue.enqueue(root);
while(!treeQueue.isEmpty())
{
System.out.print(((BinaryNode)(treeQueue.front())).element);
p=(BinaryNode)treeQueue.dequeue();
if(p.left!=null)
treeQueue.enqueue(p.left);
if(p.right!=null)
treeQueue.enqueue(p.right);
}
}
}
public class BinaryTreeTest {
/**
* @param args
*/
public static void main(String[] args) {
// TODO 自动生成方法存根
BinaryTree tree = new BinaryTree();
System.out.println("先序遍历：");
tree.preOrder();
System.out.println();
System.out.println("中序遍历：");
tree.inOrder();
System.out.println();
System.out.println("后序遍历：");
tree.postOrder();
System.out.println();
System.out.println("层次遍历：");
tree.breadthFirst();
System.out.println();
}
}
⑽ 求助！！！java二叉树貌似陷入死递归了
你的index的值没加static关键字，导致你每次在new 一个新的节点时index的值都是0