这样写有什么缺陷，求指导

package tra;

public class vehicle {

public String move;

public int num;

public void print(String moveMode,int carryNum){

this.move=moveMode;

this.num=carryNum;

System.out.println("运行方式："+move+"载客人数："+num);

}

}

package tra;

public class car extends vehicle {

public  void print(){

System.out.println("汽车运输方式："+move+"  载客人数："+num);

}

}

package tra;

public class ferry extends vehicle {

public void print(){

System.out.println("轮船运输方式："+move+"  载客人数："+num);

}

}

package tra;

public class test {

/**

* @param args

*/

public static void main(String[] args) {

// TODO Auto-generated method stub

        vehicle b1 = new car();

        b1.print("陆行",5);

        vehicle b2 = new plan();

        b2.print("飞行", 300);

        vehicle b3 = new ferry();

        b3.print("水航", 500);

}

}