我有使用instanceof和cast的这种代码，我想避免它们：

class Vehicle {}

class Boat extends Vehicle {
    getFloating()
}

class Car extends Vehicle{
    getWheels()
}

class UseVehicle{
    void useVehicleAsCar(Vehicle vehicle){ 
// this method cant be change its parameter Vehicle,of course ;D

        if (vehicle instanceof Car){
           ((Car)vehicle).getWheels() 
        }
    }
}

解决方案可以如下：

abstract class Vehicle {
    Car asCar(){return null;}
    Boat asBoat(){return null;}
}

class Boat extends Vehicle {
    getFloating(){};
    Boat asBoat(){return this};

}

class Car extends Vehicle{
    getWheels(){}
    Car asCar(){return this;}
}

class UseVehicle{
    void useVehicleAsCar(Vehicle vehicle){ 
// accept in exemple that object param is an instance of Car

        vehicle.asCar().getWheels(); 
    }
}

但是现在车辆班级认识孩子....如果我要上公交车班级，我必须在超级班级中添加方法

你有更好的东西吗？