4.7 Java4040r review  (Page 2/3)

True or False? The program shown in Listing 1 compares the search speed of the ArrayList class and the TreeSet class.

Answer 9

Question 10

True or False? The program shown in Listing 1 instantiates a TreeSet object and populates it with approximately 10,000,000 elements.

Answer 10

Question 11

True or False? Because the add method of a Set object rejects duplicate elements, there may be fewer than 2,000,000 elements in the TreeSet object in Listing 1 after it is populated, depending on how many of the random values are duplicates.

Answer 11

Question 12

True or False? One of the capabilities of the Collection Framework is to create a new Collection object and populate it with the contents of an existing Collection object of a different (or the same) actual type.

Answer 12

Question 13

True or False? The code in Listing 1 instantiates an ArrayList object and populates it with exactly 2,000,000 random values that are different from the random valuescontained in the TreeSet object.

Answer 13

Question 14

True or False? The ArrayList object in Listing 1 may contain duplicate values.

Answer 14

Question 15

True or False? Listing 1 calls the get method on the ArrayList object. The ArrayList class implements the List interface. The get method of the List interface is inherited from the Collection interface.

Answer 15

Question 16

True or False? In general, the time required for the contains method to find a value in a TreeSet object is less than the time required for the contains method to find a value in an ArrayList object.

Answer 16

Question 17

True or False? The very fast searching speed of a TreeSet object results from the implementation of the Set interface.

Answer 17

Question 18

True or False? Polymorphic behavior means that the actual method that is executed on a Collection object is the appropriate method for that type of object regardless of the actual type (class) of the reference to the object.

Answer 18

Question 19

True or False? Some of the implementations of the Java Collections Framework maintain their elements in a random order, and other implementations maintaintheir elements in a sorted order. The sorting algorithms used to maintain the order of the collections in the Collections Framework are exposed in the sameway that the search algorithm is exposed (via the contains method).

Answer 19

Question 20

True or False? The interfaces in the Collections Framework make it possible to manipulate the contents of collections in a manner that is independent of the underlying implementation of each collection.

Answer 20

Listings

• Listing 1 . Used for several questions.

What is the meaning of the following two images?

These images were inserted here simply to insert some space between the questions and the answers to keep them from being visible on the screen at thesame time.

This image was also inserted for the purpose of inserting space between the questions and the answers.

Answers

Answer 20

True.

Back to Question 20

Answer 19

False. The sorting algorithms used to maintain the order of the collections in the Collections Framework are not exposed in the way that the searchalgorithm is exposed (via the contains method). Rather, the sorting algorithms are implicit in those implementations that need them, and are absent from thoseimplementations that don't need them.