程式碼:

package inheritance_interface;

interface Runner {   public void run();}

class Locomotion {}

class Vehicle {}

class Car extends Vehicle {   String hood;}

class SportsCar extends Car implements Runner {   public void run() {   }}

class Motorcycle implements Runner {   public void run() {   }}

public class Howto {}

which of the following is true of the above?

A.Motorcycle is an Vehicle.

B.Motorcycle is a Run.

C.Car is a Vehicle.

D.Car is a Runner.

E.Motorcyle has a String.

G.Sports car has a Runner.

答案：B、C、F

這是來自徹底征服SCJP 6認證，p.4-104，試題51的問題！

問題的解釋很詭異：

選項A是正確的，Motorcycle雖然實作了Runner介面但是卻沒有繼承Vehicle所以Motorcycle並不是一個Vehicle。=>都說不是Vehicle了，還說A是正確的？答案也沒有A啊，解釋詭異1

選項B就是正確的了，因為Motorcycle實作了Runner介面所以Motorcylce是一個Runner這個說法沒錯。啊怎跟題目的Motorcycle is a Run不一致？這是題意、答案、解釋不一致的詭異2

選項E是錯誤的，Motorcycle有一個Vehicle，可是我們檢視的結果Motorcycle以及其所實作的Runner介面都沒有Vehicle 這個屬性，所以這個選項錯誤。感覺是Motorcycle有一個Vehicle是真兌現什世界說的，後面的說法是根據題意說的！

選項G的Sports car還分一個空格說，真不知該怎麼說這個排版！

所以個人覺得答案只有C跟F，不知各位的高見如何？還煩請解惑，謝謝！

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Tags: SCJP, scjp 1.6, scjp 6, scjp 6.0, scjp test

This entry was posted on 星期一, 十一月 9th, 2009 at 4:52 下午 and is filed under java. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
本文在2009/11/09修改。