import java.util.*;
2. public class Test {
3. // calcCache will reference a large HashMap that is
4. // only needed for the duration of doComputation().
5. private Map calcCache = null;
6. public void doWork() {
7. init();

8. doComputation();
9. // Insert code fragment here
10. }
11. private void init() { // initialize calcCache code here ...
12. }
13. private void doComputation() { // computation code here ...
14. }
15.}
What code fragment is added to the sample code at Line 9 above to allow the memory held by the large HashMap to be reclaimed by the system garbage collector?
Choice 1 System.getRuntime().dealloc(calcCache);
Choice 2 System.free(calcCache);
Choice 3 calcCache = null;
Choice 4 dealloc(calcCache);
Choice 5 free calcCache;