java实现递归树

㈠ java递归数据库生成菜单树

代码截图摘自开源框架《若依》网页链接

㈡ java 用递归创建二叉树，非递归遍历二叉树输出节点

我自己用递归写了下，不知道能不能给你帮助：

测试类：
package tree;

import java.util.*;

public class Test {

public static void main(String[] args){
List<Tree> trees=new ArrayList<Tree>();
int id=1;
Tree tree1=new Tree(0,id++,"张三丰");
Tree tree2=new Tree(tree1.getId(),id++,"武当宋大侠宋远桥");
Tree tree3=new Tree(tree1.getId(),id++,"武当俞二侠俞莲舟");
Tree tree4=new Tree(tree1.getId(),id++,"武当俞三侠俞岱岩");
Tree tree5=new Tree(tree1.getId(),id++,"武当张四侠张松溪");
Tree tree6=new Tree(tree1.getId(),id++,"武当张五侠张翠山");
Tree tree7=new Tree(tree1.getId(),id++,"武当殷六侠殷梨亭");
Tree tree8=new Tree(tree1.getId(),id++,"武当莫七侠莫声谷");
Tree tree9=new Tree(tree6.getId(),id++,"明教张无忌");
Tree tree13=new Tree(tree2.getId(),id++,"叛徒宋青书");

Tree tree10=new Tree(0,id++,"任我行");
Tree tree11=new Tree(tree10.getId(),id++,"令狐冲");
Tree tree12=new Tree(tree10.getId(),id++,"任盈盈");

trees.add(tree1);
trees.add(tree2);
trees.add(tree3);
trees.add(tree4);
trees.add(tree5);
trees.add(tree6);
trees.add(tree7);
trees.add(tree8);
trees.add(tree9);
trees.add(tree10);
trees.add(tree11);
trees.add(tree12);
trees.add(tree13);

for(int i=0;i<trees.size();i++){
Tree tree=trees.get(i);
if(tree.getParentId()==0){
tree.showChildTree(trees);
}
}

}

}

树类：
package tree;

import java.util.List;

public class Tree {
private int parentId;
private int id;
private String showStr;
private String Spaces="";

public Tree() {
// TODO Auto-generated constructor stub
}
public Tree(int parentId,int id,String showStr){
this.parentId=parentId;
this.id=id;
this.showStr=showStr;
}

public void showChildTree(List<Tree> trees){
if(parentId!=0){
trees.get(id-1).setSpaces(trees.get(parentId-1).getSpaces()+" ");
}
System.out.println(trees.get(id-1).getSpaces()+showStr);
for(int i=0;i<trees.size();i++){
Tree tree=trees.get(i);
if(tree.getParentId()==id){
tree.showChildTree(trees);
}
}

}

public int getParentId() {
return parentId;
}

public void setParentId(int parentId) {
this.parentId = parentId;
}

public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}

public String getShowStr() {
return showStr;
}

public void setShowStr(String showStr) {
this.showStr = showStr;
}

public String getSpaces() {
return Spaces;
}

public void setSpaces(String spaces) {
Spaces = spaces;
}

}

效果图：
张三丰
武当宋大侠宋远桥
叛徒宋青书
武当俞二侠俞莲舟
武当俞三侠俞岱岩
武当张四侠张松溪
武当张五侠张翠山
明教张无忌
武当殷六侠殷梨亭
武当莫七侠莫声谷
任我行
令狐冲
任盈盈

㈢ Java递归如何正确输出树形菜单

首先我们要建立树节点的类：
[java] view plain
package com.tree;

public class Node {
private Integer id;
private Integer parentId;
private String name;
private String link;

public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public Integer getParentId() {
return parentId;
}
public void setParentId(Integer parentId) {
this.parentId = parentId;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getLink() {
return link;
}
public void setLink(String link) {
this.link = link;
}
}
输出树形菜单类：
[java] view plain
package com.tree;

import java.util.ArrayList;
import java.util.List;

public class Tree {
private StringBuffer html = new StringBuffer();
private List<Node> nodes;

public Tree(List<Node> nodes){
this.nodes = nodes;
}

public String buildTree(){
html.append("<ul>");
for (Node node : nodes) {
Integer id = node.getId();
if (node.getParentId() == ) {
html.append("\r\n<li id='" + id + "'>" + node.getName()+ "</li>");
build(node);
}
}
html.append("\r\n</ul>");
return html.toString();
}

private void build(Node node){
List<Node> children = getChildren(node);
if (!children.isEmpty()) {
html.append("\r\n<ul>");
for (Node child : children) {
Integer id = child.getId();
html.append("\r\n<li id='" + id + "'>" + child.getName()+ "</li>");
build(child);
}
html.append("\r\n</ul>");
}
}

private List<Node> getChildren(Node node){
List<Node> children = new ArrayList<Node>();
Integer id = node.getId();
for (Node child : nodes) {
if (id.equals(child.getParentId())) {
children.add(child);
}
}
return children;
}
}

㈣ 如何利用java递归遍历得到树

你这个是Oracle吧.
父子节点是DEPTID和FDEPTID吧?
Oracle里面有一条语句是专门用来处理树的,
select...start with... connect by ...prior
大概是 select * from table start with DEPTID=1 connect by prior DEPTID=FDEPTID
我很久没用过Oracle了,可能上面这条sql是错的....具体你参考一下网上的消息吧.

㈤ 用java递归方法实现

publicintfun(intn){
if(n==0||n==1)return1;
returnn*fun(n-1);
}

㈥ java使用递归实现树形结构

inserttb_menu(id,name,parent)(640000000000,北京市,0);
inserttb_menu(id,name,parent)(640100000000,昌平区,1);
inserttb_menu(id,name,parent)(640101000000,霍营,2);
inserttb_menu(id,name,parent)(640101001000,回龙观东大街,3);

添加一个节点属性， 根据数据不同代表的地位不同，0就代表父节点 ，1是0的子节点，2是1的子节点，以此类推。

㈦ AVL树所有的java递归算法

http://www.doc88.com/p-292361550358.html

㈧ 用java递归方法实现数据库树形结构的展示，如果在数据库中新增一个节点，要保证能展示出来这应该怎么做

将增加的节点设置为某个节点的孩子节点即可。

㈨ java 递归数据库生成 树形结构问题

1、准备表结构及对应的表数据
a、表结构：
create table TB_TREE
(
CID NUMBER not null,
CNAME VARCHAR2(50),
PID NUMBER //父节点
)

b、表数据：

insert into tb_tree (CID, CNAME, PID) values (1, '中国', 0);
insert into tb_tree (CID, CNAME, PID) values (2, '北京市', 1);
insert into tb_tree (CID, CNAME, PID) values (3, '广东省', 1);
insert into tb_tree (CID, CNAME, PID) values (4, '上海市', 1);
insert into tb_tree (CID, CNAME, PID) values (5, '广州市', 3);
insert into tb_tree (CID, CNAME, PID) values (6, '深圳市', 3);
insert into tb_tree (CID, CNAME, PID) values (7, '海珠区', 5);
insert into tb_tree (CID, CNAME, PID) values (8, '天河区', 5);
insert into tb_tree (CID, CNAME, PID) values (9, '福田区', 6);
insert into tb_tree (CID, CNAME, PID) values (10, '南山区', 6);
insert into tb_tree (CID, CNAME, PID) values (11, '密云县', 2);
insert into tb_tree (CID, CNAME, PID) values (12, '浦东', 4);

2、TreeNode对象，对应tb_tree

public class TreeNode implements Serializable {
private Integer cid;
private String cname;
private Integer pid;
private List nodes = new ArrayList();

public TreeNode() {
}

//getter、setter省略
}

3、测试数据

public class TreeNodeTest {
@Test
public void loadTree() throws Exception{
System.out.println(JsonUtils.javaToJson(recursiveTree(1)));
}

/**
* 递归算法解析成树形结构
*
* @param cid
* @return
* @author jiqinlin
*/
public TreeNode recursiveTree(int cid) {
//根据cid获取节点对象(SELECT * FROM tb_tree t WHERE t.cid=?)
TreeNode node = personService.getreeNode(cid);
//查询cid下的所有子节点(SELECT * FROM tb_tree t WHERE t.pid=?)
List childTreeNodes = personService.queryTreeNode(cid);
//遍历子节点
for(TreeNode child : childTreeNodes){
TreeNode n = recursiveTree(child.getCid()); //递归
node.getNodes().add(n);
}

return node;
}
}

输出的json格式如下：

{
"cid": 1,
"nodes": [
{
"cid": 2,
"nodes": [
{
"cid": 11,
"nodes": [

],
"cname": "密云县",
"pid": 2
}
],
"cname": "北京市",
"pid": 1
},
{
"cid": 3,
"nodes": [
{
"cid": 5,
"nodes": [
{
"cid": 7,
"nodes": [

],
"cname": "海珠区",
"pid": 5
},
{
"cid": 8,
"nodes": [

],
"cname": "天河区",
"pid": 5
}
],
"cname": "广州市",
"pid": 3
},
{
"cid": 6,
"nodes": [
{
"cid": 9,
"nodes": [

],
"cname": "福田区",
"pid": 6
},
{
"cid": 10,
"nodes": [

],
"cname": "南山区",
"pid": 6
}
],
"cname": "深圳市",
"pid": 3
}
],
"cname": "广东省",
"pid": 1
},
{
"cid": 4,
"nodes": [
{
"cid": 12,
"nodes": [

],
"cname": "浦东",
"pid": 4
}
],
"cname": "上海市",
"pid": 1
}
],
"cname": "中国",
"pid": 0
}

㈩ java怎么递归出一棵树来，表结构为 int id,int pid,varchar text,varchar url,

要递归树结构必须要层级关系。你给的字段是什么表示？