java树结构

package com.ri;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
import org.apache.commons.lang3.ArrayUtils;
import org.checkerframework.checker.units.qual.m;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.google.common.collect.ImmutableMap;
public class Tre {
    
	//JSON.parseObject(jsonStr, new TypeReference<List>() {});  
    public static void main(String[] args) {
   
    	    //已有树结构转对象
    	    String jsonStr = "[{\"parentID\":0,\"id\":1,\"name\": \"商品一级菜单\",\"type\": \"商品\",\"code\": \"0001\",\"childMenu\":[{\"parentID\":1,\"id\":2,\"name\": \"商品二级菜单\",\"type\": \"商品\",\"code\": \"0001\",\"childMenu\":[{\"parentID\":2,\"id\":3,\"name\": \"商品三级菜单\",\"type\": \"商品\",\"code\": \"0001\",\"childMenu\":[]}]}]}]";
    	    List<MenuItem> menuItems = JSON.parseArray(jsonStr, MenuItem.class);
    	    
    	    
            // 控制展示层级为1级
    	    //menuItems = collectChildMenu(menuItems, 1, 0);
            // 打印结果
    	    //for (MenuItem item : menuItems) {
   
    	    //    System.out.println(item.getName());
    	    //}

            
             
            //树结构转扁平化对象
            List<MenuItem> flatMenuList = new ArrayList<>();
            flattenMenu(menuItems, flatMenuList);
    	    for (MenuItem item : flatMenuList) {
   
    	        System.out.println(item);