public Car out(Ticket ticket) {
        Car car = null;
        for(Park park : this.parkList) {
            try{
                if((car = park.out(ticket)) != null) {
                    return car;
                }
            } catch (ParkException e) {
            }
            if(car != null) {
                break;
            }
        }
        throw new ParkException("没有您要取的车！");
    }