SCJP題庫第122題
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.
Ans: D
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。
Comments