java练习题，这段运行不出来，谢谢

Question

题目是使用接口比较汽车速度的大小

//主类

public class tVehicle extends Vehicle{
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Vehicle a=new Vehicle();
        a.speedup();
        Vehicle b=new Vehicle();
        b.speedup();
        b.speedup();
        int a1;
        a1=a.speed;
        int b1;
        b1=b.speed;
        compare( a1, b1);    }

}



//Vehicle类

public class Vehicle implements Comparable{
int speed=0;
public void speedup() {
    speed+=10;
}
public void slowdown() {
    speed-=10;
}
public void showinfo() {
    System.out.println(speed);
}
public String tostring() {
    return "I'm a vehicle";
}
public void compare(int a,int b){

    if(a>b)
        System.out.println("a速度大");
    else
        System.out.println("b速度大");

}
}



//接口类
public interface Comparable {
    public void compare(int a,int b) ;
}

Answer 1

有个东西叫ide

就算没有ide，编译下，编译器也会告诉你错误