请定义一个交通工具(Vehicle)的类，其中有: 属性：速度(speed)，体积(size)等等

 1 public class Vehicle {
 2     double speed;
 3     double size;
 4     Vehicle(){
 5         speed=1.0;
 6         size=2.0;
 7     }
 8     void move(){    
 9     }
10     void setSpeed(int speed){
11         this.speed=speed;
12     }
13     void setSize(int size){
14         this.size=size;
15     }
16     void speedUp(){
17         speed=speed+1;
18         System.out.println("汽车加速后的速度为"+speed+"千米/时");
19     }
20     void speedDown(){
21         speed=speed-1;
22         System.out.println("汽车减速后的速度为"+speed+"千米/时");
23     }
24 }
25 --------------------------------------------------------------------------------
26 public class Test {
27 
28     public static void main(String[] args) {
29         // TODO Auto-generated method stub
30         Vehicle aaa=new Vehicle();
31         System.out.println("汽车的速度为"+aaa.speed+"千米/时");
32         System.out.println("汽车的体积为"+aaa.size+"立方米");
33         aaa.speedUp();
34         aaa.speedDown();
35     }
36 
37 }