java list转换为树形结构数据

/**
 * 转换为树形结构数据
 *
 * @param authMenuVOList 列表数据
 * @return 树形列表数据
 */
private List<AuthMenuVO> transListToTreeList(List<AuthMenuVO> authMenuVOList) {
    List<AuthMenuVO> rootMenuList = Lists.newArrayList();
    Map<Long, AuthMenuVO> menuNodeMap = Maps.newHashMap();
    for (AuthMenuVO authMenuVO : authMenuVOList) {
        menuNodeMap.put(authMenuVO.getId(), authMenuVO);
    }
    //遍历列表数据，添加到父节点下，如果是根节点存入根节点列表中，如果不是根节点添加到父节点下
    for (AuthMenuVO authMenuVO : authMenuVOList) {
        Long pid = authMenuVO.getPid();
        //判断是否是跟节点
        if (pid == 0) {
            rootMenuList.add(authMenuVO);
        } else {
            AuthMenuVO parentMenu = menuNodeMap.get(pid);
            List<AuthMenuVO> childrenList = parentMenu.getChildren();
            if (childrenList == null) {
                childrenList = Lists.newArrayList();
                parentMenu.setChildren(childrenList);
            }
            childrenList.add(authMenuVO);
        }
    }
    return rootMenuList;
}