3、写实体类(交通工具)，有速度和体积变量和加速减速方法，然后在测试类中实例对象调用方法进行测试（参考之前作过的类似实验)

public class Vehicle {
    public static void main(String[] args) {
        Vehicle vehicle = new Vehicle(12, 1000);
        System.out.println(vehicle);
        vehicle.speedUp();        
        System.out.println("加速后："+vehicle);
        vehicle.speedDown();
        System.out.println("减速后："+vehicle);
    }
    private double speed;
    private double size;
    public Vehicle() {
        super();
    }
    public Vehicle(double speed, double size) {
        super();
        this.speed = speed;
        this.size = size;
    }
    public double getSpeed() {
        return speed;
    }
    public void setSpeed(double speed) {
        this.speed = speed;
    }
    public double getSize() {
        return size;
    }
    public void setSize(double size) {
        this.size = size;
    }
    public void move() {
    }
    public void speedUp() {
        speed++;
    }
    public void speedDown() {
        speed--;
    }
    @Override
    public String toString() {
        return "Vehicle [speed=" + speed + ", size=" + size + "]";
    }
}