public interface VehicleInterface{ public void run(); }public abstract class Vehicle implements VehicleInterface{ public void run(){ } }public class Car extends Vehicle{ public void run(){ super.run(); } }
大神帮忙给修改补充一下? public interface VehicleInterface { public abstract void start(); public abstract void stop(); }================================== public abstract class Vehicle implements VehicleInterface { int registrationNumber; Person owner; private String brand; Double price; void transferOwnership(Person newOwner) { } }class Person {} ====================================public class Car extends Vehicle{ private int id; private int colorId; int numberOfDoors;
public Car() { super(); System.out.println("inside the constructor"); }
public void run();
}public abstract class Vehicle implements VehicleInterface{
public void run(){
}
}public class Car extends Vehicle{
public void run(){
super.run();
}
}
public interface VehicleInterface {
public abstract void start();
public abstract void stop();
}==================================
public abstract class Vehicle implements VehicleInterface {
int registrationNumber;
Person owner;
private String brand;
Double price; void transferOwnership(Person newOwner) { }
}class Person {}
====================================public class Car extends Vehicle{
private int id;
private int colorId;
int numberOfDoors;
public Car() {
super();
System.out.println("inside the constructor");
}
setId(id){};
getId(){};
public void start(){
}
public void stop(){
}
}
上面2句1&2必须有吗?
abstract public void run();
吗?
我试了一下,如果是abstract class,可以不写public void run(){ }但如果不是abstract class,则一定要写public void run(){ }
到底应不应该用abstract class?