Module 7- 集合和泛型.docxVIP

Copyright Tarena Corporation,2008.All rights reservedModule 7- 集合和泛型一、选择题： Question 1Given:11. public class Person {12. private name;13. public Person(String name) {14. = name;15. }16. public int hashCode() {17. return 420;18. }19. }Which is true?A. The time to find the value from HashMap with a Person key dependson the size of the map.B. Deleting a Person key from a HashMap will delete all map entries forall keys of type Person.C. Inserting a second Person object into a HashSet will cause the firstPerson object to be removed as a duplicate.D. The time to determine whether a Person object is contained in aHashSet is constant and does NOT depend on the size of the map.Answer: AQuestion 2Given:11. public static Collection get() {12. Collection sorted = new LinkedList();13. sorted.add( B ); sorted.add( C ); sorted.add( A );14. return sorted;15. }16. public static void main(String[] args) {17. for (Object obj: get()) {18. System.out.print(obj + , );19. }20. }What is the result?A. A, B, C,B. B, C, A,C. Compilation fails.D. The code runs with no output.E. An exception is thrown at runtime.Answer: BCopyright Tarena Corporation,2008.All rights reservedQuestion 3Given:1. import java.util.*;2. public class Example {3. public static void main(String[] args) {4. // insert code here5. set.add(new integer(2));6. set.add(new integer(l));7. System.out.println(set);8. }9. }Which code, inserted at line 4, guarantees that this program willoutput [1, 2]?A. Set set = new TreeSet();B. Set set = new HashSet();C. Set set = new SortedSet();D. List set = new SortedList();E. Set set = new LinkedHashSet();Answer: AQuestion 4Given:1. import java.util.*;2. public class PQ {3. public static void main(String[] args) {4. PriorityQueueString pq = new PriorityQueueString();5. pq.add( carrot );6. pq.add( apple );7. pq.add( banana );8. System.out.println(pq.poll() + : + pq.peek());9. }10. }What is the result?A. apple:appleB. carrot:appleC. apple:bananaD. banana:appleE. carrot:carrotF.