java 递归遍历树形结构

好记性不如烂笔头，记录下。//菜单树形结构     public JSONArray treeMenuList(JSONArray menuList, int parentId) {         JSONArray childMenu = new JSONArray();         for (Object object : menuList) {             JSONObject jsonMenu = JSONObject.fromObject(object);             int menuId = jsonMenu.getInt("id");             int pid = jsonMenu.getInt("parentId");             if (parentId == pid) {                 JSONArray c_node = treeMenuList(menuList, menuId);                 jsonMenu.put("childNode", c_node);                 childMenu.add(jsonMenu);             }         }         return childMenu;     }  public static void main(String args[]) {         MenuCacheService menuCacheService = new MenuCacheService();         JSONArray jsonArray = new JSONArray();         Menu menu1 = new Menu();         menu1.setId(1l);         menu1.setParentId(0);         menu1.setLevel(0);         Menu menu2 = new Menu();         menu2.setId(2l);         menu2.setParentId(0);         menu2.setLevel(0);         Menu menu3 = new Menu();         menu3.setId(3l);         menu3.setParentId(2);         menu3.setLevel(1);         Menu menu4 = new Menu();         menu4.setId(4l);         menu4.setParentId(2);         menu4.setLevel(1);         Menu menu5 = new Menu();         menu5.setId(5l);         menu5.setParentId(4);         menu5.setLevel(2);         Menu menu6 = new Menu();         menu6.setId(6l);         menu6.setParentId(1);         menu6.setLevel(1);         jsonArray.add(menu1);         jsonArray.add(menu2);         jsonArray.add(menu3);         jsonArray.add(menu4);         jsonArray.add(menu5);         jsonArray.add(menu6);         System.out.print(menuCacheService.treeMenuList(jsonArray,0));     }