SCJP題庫第074題

Which two classes correctly implement

both the java.lang.Runnable

and the java.lang.Cloneable interfaces? (Choose two.)

 

A. public class Session

implements Runnable, cloneable {

        public void run();

        public Object clone();

}

B. public class Session

extends Runnable, Cloneable {

        public void run(){/* do something */}

        public Object clone(){/* make a copy */}

}

C. public class Session

implements Runnable, Cloneable {

        public void run(){/* do something */}

        public Object clone() {/* make a copy */}

}

D. public abstract class Session

implements Runnable, Cloneable {

        public void run(){/* do something */}

        public Object clone(){/* make a copy */}

}

E. public class Session

implements Runnable, implements Cloneable {

        public void run(){/* do something */}

        public Object clone() {/* make a copy */}

}

 

 

Ans: C D

 

解說:

此題問那二個類別正確地實作Runnable與Cloneable介面

A錯是因為既然實作了介面，就必須把介面中的抽象方法實作寫出來，run和clone方法依然是抽象的。

B錯是類跑不能用extends去繼承介面

E錯是寫法不對(要如C和D寫法)