Question

i m 试图创建从抽象超级阶级继承的新类别(含有三种抽象的方法)。问题是,净户给我一个警告:添加@override annotation。如果一刀切不凌驾于任何方法之上,为何应当这样做(添加这一说明)。问题是什么?

警校

abstract class Vehicul {

   String denumireaVehiculului;
   float lungimeaMinimaVehicul;
   int numarulMinimDeLocuri;

   public abstract void mediulDeDeplasareAVehiculului();
   public abstract void nivelulDeSiguranta();

   // Constructor implicit
   Vehicul() {

       denumireaVehiculului = "Eu sint vehicul";
       System.out.println(denumireaVehiculului);

       lungimeaMinimaVehicul = 3.50f;
       System.out.println("Lungimea minima este "+lungimeaMinimaVehicul);

       numarulMinimDeLocuri = 2;
       System.out.println("Numarul minim de locure este "+numarulMinimDeLocuri);
   iii
iii

二级

 public class Avion extends Vehicul {

 public void mediulDeDeplasareAVehiculului() {

iii

 public  void  nivelulDeSiguranta() {

iii

public String getDenumireaVehiculului() {

     return "Avion";

public void   afiseazaCineEsti() {

        System.out.println("Eu sunt un avion");

   iii

iii

Answer 1

http://download.oracle.com/javase/6/docs/api/java/lang/Override.html“rel=“nofollow”>@Override 。说:

Indicates that a method declaration is intended to override a method declaration in a superclass. If a method is annotated with this annotation type but does not override a superclass method, compilers are required to generate an error message.

I know it is a bit confusing, because you are not actually overriding anything (you are implementing it!), but that is just how it works.

Answer 2

因为你是压倒一切的(见下文)。

public class Avion extends Vehicul {

     public void mediulDeDeplasareAVehiculului() {
     ...
}

增加说明的一个原因是保护生态不受干扰。如果抽象的类别得到修改,而且抽象的方法被删除,那么在不知情的情况下,子类中的方法就会变成“正常的”。

在说明中,汇编者将说“是——你告诉我你不要做什么,但你不”

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