Ikk：新頁面: 11. class Person{ 12. String name = "No name"; 13. public Person(String nm){name = nm;} 14. } 15. 16. class Employee extends Person{ 17. String empID = "0000"; 18. publ...

2013-03-30T08:47:34Z

新頁面: 11. class Person{ 12. String name = "No name"; 13. public Person(String nm){name = nm;} 14. } 15. 16. class Employee extends Person{ 17. String empID = "0000"; 18. publ...

新頁面

11. class Person{
12. String name = "No name";
13. public Person(String nm){name = nm;}
14. }
15.
16. class Employee extends Person{
17. String empID = "0000";
18. public Employee(String id){empID = id;}
19. }
20.
21. class EmployeeTest{
22. public static void main(String[] args){
23. Employee e = new Employee("4321");
24. System.out.println(e.empID);
25. }
26. }

What is the result?
A. 4321
B. 0000
C. An exception is thrown at runtime.
D. Compilation fails because of an error in line 18.

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

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

<span style="font-size:medium;"> 解說:
下面二個方法以第2種方法較好，記得有一個黃金定律，一個類別裏，不管如何，都要有一個無參數的建構子…！
1.
class Employee extends Person{
String empID = "0000";
public Employee(String id){super(id); empID = id;}
}

2.
class Person{
String name = "No name";
public Person(String nm){name = nm;}
public Person(){}
}

</span>
</div></div>
{{SCJP 1.6版考題講解}}
Ans:D
解說:

SCJP 1.6版考題 014 - 修訂歷史

Ikk：新頁面: 11. class Person{ 12. String name = "No name"; 13. public Person(String nm){name = nm;} 14. } 15. 16. class Employee extends Person{ 17. String empID = "0000"; 18. publ...