Java 단순 트리 구조 구현

package com.app;
 
 import java.util.ArrayList;
 import java.util.List;
 
 public class treeNode<T> {
   public T t;
   private treeNode<T> parent;
   
   public List<treeNode<T>> nodelist;
   
   public treeNode(T stype){
     t   = stype;
     parent = null;
     nodelist = new ArrayList<treeNode<T>>();
   }
 
   public treeNode<T> getParent() {
     return parent;
   }  
 }

package com.app;
 
 public class tree<T> {
   
   public treeNode<T> root;
   
   public tree(){}
     
   public void addNode(treeNode<T> node, T newNode){
     // 
     if(null == node){
       if(null == root){
         root = new treeNode(newNode);
       }
     }else{
         treeNode<T> temp = new treeNode(newNode);
         node.nodelist.add(temp);
     }
   }
   
   /*   newNode  */
   public treeNode<T> search(treeNode<T> input, T newNode){
   
     treeNode<T> temp = null;
     
     if(input.t.equals(newNode)){
       return input;
     }
     
     for(int i = 0; i < input.nodelist.size(); i++){
       
       temp = search(input.nodelist.get(i), newNode);
       
       if(null != temp){
         break;
       }  
     }
     
     return temp;
   }
   
   public treeNode<T> getNode(T newNode){
     return search(root, newNode);
   }
   
   public void showNode(treeNode<T> node){
     if(null != node){
       // node 
       System.out.println(node.t.toString());
       
       for(int i = 0; i < node.nodelist.size(); i++){
         showNode(node.nodelist.get(i));
       }      
     }
   }
 }

package com.app;
 
 public class app {
 
   /**
    * @param args
 */
   public static void main(String[] args) {
     // TODO Auto-generated method stub
     /* ， xml       */
     /* ，         2012-3-12  */
     // 
     /*
     * string
     *     hello
     *       sinny
     *       fredric
     *     world
     *      Hi
     *      York
     * */
     
     tree<String> tree = new tree();
     tree.addNode(null, "string");
     tree.addNode(tree.getNode("string"), "hello");
     tree.addNode(tree.getNode("string"), "world");
     tree.addNode(tree.getNode("hello"), "sinny");
     tree.addNode(tree.getNode("hello"), "fredric");
     tree.addNode(tree.getNode("world"), "Hi");
     tree.addNode(tree.getNode("world"), "York");
     tree.showNode(tree.root);
     
     System.out.println("end of the test");
   }
 
 }