编写一个java 继承 多态的案例

以下是一个简单的Java继承多态案例，演示如何使用继承和多态来创建不同类型的车辆对象和相应的属性：

public class Vehicle {
    protected String make;
    protected String model;
    protected int year;

    public Vehicle(String make, String model, int year) {
        this.make = make;
        this.model = model;
        this.year = year;
    }

    public void start() {
        System.out.println("Starting vehicle...");
    }

    public void stop() {
        System.out.println("Stopping vehicle...");
    }
}

public class Car extends Vehicle {
    private int numDoors;

    public Car(String make, String model, int year, int numDoors) {
        super(make, model, year);
        this.numDoors = numDoors;
    }

    public void drive() {
        System.out.println("Driving car...");
    }
}

public class Truck extends Vehicle {
    private int towingCapacity;

    public Truck(String make, String model, int year, int towingCapacity) {
        super(make, model, year);
        this.towingCapacity = towingCapacity;
    }

    public void haul() {
        System.out.println("Hauling truck...");
    }
}

public class Main {
    public static void main(String[] args) {
        Vehicle myVehicle = new Vehicle("Honda", "Civic", 2020);
        Car myCar = new Car("Toyota", "Corolla", 2019, 4);
        Truck myTruck = new Truck("Ford", "F-150", 2018, 10000);

        myVehicle.start();
        myVehicle.stop();

        myCar.start();
        myCar.drive();
        myCar.stop();

        myTruck.start();
        myTruck.haul();
        myTruck.stop();
    }
}

在这个例子中，Vehicle类是一个基本的车辆类，其中包含所有车辆都共享的属性和方法。Car和Truck类继承自Vehicle，并添加了它们各自独有的属性和方法。在Main类中，我们创建了三个不同类型的车辆对象，并调用它们各自的方法来演示多态的使用