SCJP題庫第099題
3. interface Animal{void makeNoise();}
4. class Horse implements Animal{
5. Long weight = 1200L;
6. public void makeNoise(){System.out.println("whinny");}
7. }
8. public class lcelandic extends Horse{
9. public void makeNoise(){System.out.println("vinny");}
10. public static void main(String[] args) {
11. Icelandic i1 = new lcelandic();
12. Icelandic i2 = new lcelandic();
13. Icelandic i3 = new lcelandic();
14. i3 = i1; i1 = i2; i2 = null; i3 = i1;
15. }
16.}
When line 14 is reached, how many objects are eligible for the garbage collector?
A. 0
B. 1
C. 2
D. 3
E. 4
F. 6
Ans: C
解說:
i3=i1，i3原本指向的物件可回收，i1=i2， i1原本指向的物件因被i3參考不能被回收，i2=null，i2指向的物件被i1參考不能回收，i3=i1，i3指向的物件可回收
可以畫圖來看比較清楚。
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