Java递归如何正确输出树形菜单

本文实例为大家分享了java递归输出树形菜单的具体代码，供大家参考，具体内容如下

首先我们要建立树节点的类：

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：

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() == null) { 
    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; 
 } 
} 

  然后我们来测试一下：

import java.util.arraylist; 
import java.util.list; 
 
import cn.com.tree.node; 
import cn.com.tree.tree; 
 
 
public class test { 
 
 /** 
  * @param args 
  */ 
 public static void main(string[] args) { 
  list<node> nodes = new arraylist<node>(); 
   
  node node1 = new node(); 
  node1.setid(1); 
  node1.setname("node1"); 
  node1.setparentid(null); 
  node1.setlink(null); 
  nodes.add(node1); 
   
  node node11 = new node(); 
  node11.setid(11); 
  node11.setname("node11"); 
  node11.setparentid(1); 
  node11.setlink(null); 
  nodes.add(node11); 
   
  node node111 = new node(); 
  node111.setid(111); 
  node111.setname("node111"); 
  node111.setparentid(11); 
  node111.setlink(null); 
  nodes.add(node111); 
   
  node node12 = new node(); 
  node12.setid(12); 
  node12.setname("node12"); 
  node12.setparentid(1); 
  node12.setlink(null); 
  nodes.add(node12); 
   
  node node2 = new node(); 
  node2.setid(2); 
  node2.setname("node2"); 
  node2.setparentid(null); 
  node2.setlink(null); 
  nodes.add(node2); 
   
  node node21 = new node(); 
  node21.setid(21); 
  node21.setname("node21"); 
  node21.setparentid(2); 
  node21.setlink(null); 
  nodes.add(node21); 
   
  node node3 = new node(); 
  node3.setid(3); 
  node3.setname("node3"); 
  node3.setparentid(null); 
  node3.setlink(null); 
  nodes.add(node3); 
   
  tree tree = new tree(nodes); 
  system.out.println(tree.buildtree()); 
 } 
} 

输出的结果：

<ul> 
<li id='1'>node1</li> 
<ul> 
<li id='11'>node11</li> 
<ul> 
<li id='111'>node111</li> 
</ul> 
<li id='12'>node12</li> 
</ul> 
<li id='2'>node2</li> 
<ul> 
<li id='21'>node21</li> 
</ul> 
<li id='3'>node3</li> 
</ul> 

浏览器效果：

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。