Ikk：新頁面: Given: 11. public void genNumbers(){ 12. ArrayList numbers = new ArrayList(); 13. for(int i=0; i<10; i++){ 14. int value = i * ((int)Math.random()); 15. Integer intOb...

2013-03-30T04:04:14Z

新頁面: Given: 11. public void genNumbers(){ 12. ArrayList numbers = new ArrayList(); 13. for(int i=0; i<10; i++){ 14. int value = i * ((int)Math.random()); 15. Integer intOb...

新頁面

Given:
11. public void genNumbers(){
12. ArrayList numbers = new ArrayList();
13. for(int i=0; i<10; i++){
14. int value = i * ((int)Math.random());
15. Integer intObj = new Integer(value);
16. numbers.add(intObj);
17. }
18. System.out.println(numbers);
19. }

Which line of code marks the earliest point
that an object referenced by intObj becomes a candidate for garbage collection?
A. Line 16
B. Line 17
C. Line 18
D. Line 19
E. The object is NOT a candidate for garbage collection.

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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:
intObj是宣告在for迴圈裏，這個迴圈結束之後(intObj消失)，看起來15行所建的物件都要能回收，
但是這些物件被加到numbers的ArrayList(集合物件)裏，這些物件可以透過numbers被參考到，
直到numbers這個參考變數消失，也就是genNumbers方法結束。

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{{SCJP 1.6版考題講解}}

SCJP 1.6版考題 122 - 修訂歷史

Ikk：新頁面: Given: 11. public void genNumbers(){ 12. ArrayList numbers = new ArrayList(); 13. for(int i=0; i<10; i++){ 14. int value = i * ((int)Math.random()); 15. Integer intOb...