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 stub30         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 }