Ikk：新頁面: 5. class Thingy{ Meter m = new Meter(); } 6. class Component {void go() { System.out.print("c");}} 7. class Meter extends Component {void go() { System.out.print("m"); }} 8. 9. cl...

2013-03-30T06:55:11Z

新頁面: 5. class Thingy{ Meter m = new Meter(); } 6. class Component {void go() { System.out.print("c");}} 7. class Meter extends Component {void go() { System.out.print("m"); }} 8. 9. cl...

新頁面

5. class Thingy{ Meter m = new Meter(); }
6. class Component {void go() { System.out.print("c");}}
7. class Meter extends Component {void go() { System.out.print("m"); }}
8.
9. class DeluxeThingy extends Thingy {
10. public static void main(String[] args) {
11. DeluxeThingy dt = new DeluxeThingy();
12. dt.m.go();
13. Thingy t = new DeluxeThingy();
14. t.m.go();
15. }
16. }

Which two are true? (Choose two.)
A. The output is mm.
B. The output is mc.
C. Component is-a Meter.
D. Component has-a Meter.
E. DeluxeThingy is-a Component.
F. DeluxeThingy has-a Component.

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<span style="font-size:medium;">解答</span>

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<span style="font-size: medium;">Ans: A F </span>

<span style="font-size:medium;"> 解說:
Meter繼承Component
DeluxeThingy 繼承Thingy ，Thingy 中有一個Meter物件(也是Component物件)，滿足F
因多形原則，m物件屬於Meter，因此二個go方法皆為Meter的go，印出m
</span>
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{{SCJP 1.6版考題講解}}

SCJP 1.6版考題 066 - 修訂歷史

Ikk：新頁面: 5. class Thingy{ Meter m = new Meter(); } 6. class Component {void go() { System.out.print("c");}} 7. class Meter extends Component {void go() { System.out.print("m"); }} 8. 9. cl...