class Vehicle {
    public void run() {

    }
}
class Car extends Vehicle{
    @Override
    public void run(){
        System.out.println("汽车启动了~");
    }
}
class Bicycle extends Vehicle{
    @Override
    public void run(){
        System.out.println("自行车启动了~");
    }
}
class Truck extends Vehicle{
    @Override
    public void run(){
        System.out.println("卡车启动了~");
    }
}
public class Main {
    static void main(String[] args) {
        Vehicle[] vehicles = new Vehicle[3];
        vehicles[0] = new Car();
        vehicles[1] = new Bicycle();
        vehicles[2] = new Truck();
        for (int i = 0; i < 3; i++) {
            Vehicle v = vehicles[i];
            v.run();
        }
    }
}