java中循环拼接字符串

在java中，查询某工号下用户的权限值，拼接为字符串，返回

表中数据结构如下：

查询结果如下：

拼接permissionCode值；

代码如下：

List<UpsUserRoleMenu> roleMenus = upsUserRoleMapper.selectRoleAndSysId(userId);
		String roleId = null;
		Integer sysId =null;
		for (UpsUserRoleMenu upsUserRoleMenu : roleMenus) {
			roleId = upsUserRoleMenu.getRoleId();
			sysId = upsUserRoleMenu.getSysId();
			try {				
				List<UpsRolePermissionDataparams> menus_list = upsRolePermissionDataParamersMapper
						.selectByUserId(Integer.valueOf(roleId),sysId);
				StringBuffer permission = new StringBuffer();
				if(null != menus_list && menus_list.size() != 0){					
					for(int i=0;i<menus_list.size(); i++){
						UpsRolePermissionDataparams menu = menus_list.get(i);
						if(i == 0){
							permission.append(menu.getPermissionCode());
						}else{
							permission.append(","+menu.getPermissionCode());
						}
					}
					upsUserRoleMenu.setPermission(permission.toString());				
				}
			} catch (Exception e) {
				e.printStackTrace();
			}
		}