单选题Which statement is true for the class java.util.HashSet？ （）AThe elements in the collection are ordered.BThe collection is guaranteed to be immutable.CThe elements in the collection are guaranteed to be unique.DThe elements in the collection are accesse

第1题：

Which statement is true for the class java.util.ArrayList？（）  

• A、 The elements in the collection are ordered.
• B、 The collection is guaranteed to be immutable.
• C、 The elements in the collection are guaranteed to be unique.
• D、 The elements in the collection are accessed using a unique key.
• E、 The elements in the collections are guaranteed to be synchronized.

第2题：

Which statements about the garbage collection are true？（） 

• A、 The program developer must create a thread to be responsible for free the memory.
• B、 The garbage collection will check for and free memory no longer needed.
• C、 The garbage collection allow the program developer to explicity and immediately free the memory.
• D、 The garbage collection can free the memory used java object at expect time.

第3题：

You need to store elements in a collection that guarantees that no duplicates are stored. Which two interfaces provide that capability？（）   

• A、 Java.util.Map
• B、 Java.util.Set
• C、 Java.util.List
• D、 Java.util.StoredSet
• E、 Java.util.StoredMap
• F、 Java.util.Collection

第4题：

11. class Snoochy {  12. Boochybooch；  13. public Snoochy（） { booch = new Boochy（this）； }  14. }  15.  16. class Boochy {  17. Snoochy snooch；  18. public Boochy（Snoochy s） { snooch = s； }  19. }  And the statements：  21. public static void main（String[] args） {  22. Snoochy snoog = new Snoochy（）；  23. snoog = null；  24. // more code here  25. }  Which statement is true about the objects referenced by snoog， snooch， and booch immediately after line 23 executes？（） 

• A、 None of these objects are eligible for garbage collection.
• B、 Only the object referenced by booch is eligible for garbage collection.
• C、 Only the object referenced by snoog is eligible for garbage collection.
• D、 Only the object referenced by snooch is eligible for garbage collection.
• E、 The objects referenced by snooch and booch are eligible for garbage collection.

第5题：

Which two statements are true about the hashCode method？（）

• A、The hashCode method for a given class can be used to test for object equality and object inequality for that class.
• B、The hashCode method is used by the java.util.SortedSet collection class to order the elements within that set.
• C、The hashCode method for a given class can be used to test for object inequality， but NOT objecte quality， for that class.
• D、The only important characteristic of the values returned by a hashCode method is that the distribution of values must follow a Gaussian distribution.
• E、The hashCode method is used by the java.util.HashSet collection class to group the elements within that set into hash buckets for swift retrieval.

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第13题：

Which statement is true for the class java.util.HashSet？（）  

• A、 The elements in the collection are ordered.
• B、 The collection is guaranteed to be immutable.
• C、 The elements in the collection are guaranteed to be unique.
• D、 The elements in the collection are accessed using a unique key.
• E、 The elements in the collections are guaranteed to be synchronized.

第14题：

1. import java.util.*；  2. public class TestSet {  3. enum Example { ONE， TWO， THREE }  4. public static void main（String[] args） {  5. Collection coll = new ArrayList（）；  6. coll.add（Example.THREE）；  7. coll.add（Example.THREE）；  8. coll.add（Example.THREE）；  9. coll.add（Example.TWO）；  10. coll.add（Example.TWO）；  11. coll.add（Example.ONE）；  12. Set set = new HashSet（coll）；  13. }  14. }  Which statement is true about the set variable on line 12？（） 

• A、 The set variable contains all six elements from the coll collection， and the order is guaranteed to be preserved.
• B、 The set variable contains only three elements from the coll collection， and the order is guaranteed to be preserved.
• C、 The set variable contains all six elements from the coil collection， but the order is NOT guaranteed to be preserved.
• D、 The set variable contains only three elements from the coil collection， but the order is NOT guaranteed to be preserved.

第15题：

Which of these statements concerning the collection interfaces are true？（）  

• A、Set extends Collection.
• B、All methods defined in Set are also defined in Collection.
• C、List extends Collection.
• D、All methods defined in List are also defined in Collection.
• E、Map extends Collection.

第16题：

class A {  }  class Alpha {  private A myA = new A（）；  void dolt（ A a ） {  a = null；  }  void tryIt（） {  dolt（ myA ）；  }  }  Which two statements are correct？（）  

• A、 There are no instanced of A that will become eligible for garbage collection.
• B、 Explicitly setting myA to null marks that instance to be eligible for garbage collection.
• C、 Any call on tryIt（） causes the private instance of A to be marked for garbage collection.
• D、 Private instances of A become eligible for garbage collection when instances of Alpha become eligible for garbage collection.

第17题：

You work as an application developer at Certkiller .com. Certkiller .com has been contracted to develop an application for the local bank.You have been given the responsibility of creating this application and need to store each transaction record， which is identified using a complex transaction identifier，in memory. The bank informs you that the total amount of transaction records could reach 200 per day. To achieve this， you decide to utilize one of the existing collection classes in the .NET 2.0 class library. You need to ensure that you the collection class you select is the most efficient one for storing transaction records.What should you do？（）

• A、 Select the ListDictionary collection class.
• B、 Select the HashTable collection class.
• C、 Select the Queue collection class.
• D、 Select the StringCollection collection class.

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