檢視 SCJP 1.6版考題 122 的原始碼

 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;">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}}