Q: 01 Given:
1. public class GC {
2. private Object o;
3. private void doSomethingElse(Object obj) { o = obj; }
4. public void doSomething() {
5. Object o = new Object();
6. doSomethingElse(o);
7. o = new Object();
8. doSomethingElse(null);
9. o = null;
10. }
11. }
When the doSomething method is called, after which line does the Object created in line 5 become
available for garbage collection?
A. Line 5
B. Line 6
C. Line 7
D. Line 8
E. Line 9
F. Line 10
Answer: D
Q: 02 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.
Answer: D
Q: 03 Given:
11. rbo = new ReallyBigObject();
12. // more code here
13. rbo = null;
14. /* insert code here */
Which statement should be placed at line 14 to suggest that the virtual machine expend effort toward
recycling the memory used by the object rbo?
A. System.gc();
B. Runtime.gc();
C. System.freeMemory();
D. Runtime.getRuntime().growHeap();
E. Runtime.getRuntime().freeMemory();
Answer: A
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