4.23 Java4120r: review  (Page 2/3)

Answer 13

Question 14

True or False? There is a class named Arrays that contains various methods for manipulating arrays (such as sorting and searching) . The Arrays class contains many overloaded versions of the sort method. As usual, each overloaded version of the sort method requires a different argument list.

Answer 14

Question 15

Given: Listing 1 makes two calls to overloaded sort methods of the Arrays class using the following overloaded methods. (Note that I omitted generics syntax from the signatures because generics is beyond the scope of this course .)

• sort(Object[] a)
• sort(Object[] a, Comparator c)

True or False? In Listing 1 , the call to the first sort method in the above list produces the following output:

Tom TOM Joe JOE Bill BILL

Answer 15

Question 16

True or False? In Listing 1 , the call to the second sort method in the above list produces the following output:

Tom TOM Joe JOE Bill BILL

Answer 16

Listings

• Listing 1 . Comparator05.java.

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 16

True.

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Answer 15

False. Here is what the documentation has to say about this overloaded version of the Arrays.sort method:

Sorts the specified array of objects into ascending order, according to the natural ordering of its elements. All elements in the array must implementthe Comparable interface.

According to that specification, the output would be:

BILL Bill JOE Joe TOM Tom

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Answer 14

True.

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Answer 13

True.

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Answer 12

True.

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Answer 11

False. By default, a Vector object does not sort the elements. Therefore, the output order is the same as the input order shown inthe fillIt method.

Joe Bill Tom JOE BILL TOM

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Answer 10

True.

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Answer 9

True.

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Answer 8

False. The position of each element in an ordered collection is determined by a numeric index associated with the element and is independent ofthe value of the element.

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Answer 7

True.

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Answer 6

False. Because a Vector object is a List object, (and not a Set object) it is allowed to contain duplicate elements.

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Answer 5

False. A Vector object is a List object. The Vector class implements the Collection interface and the List interface but not the Set interface.

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Answer 4

Collection data

Joe Bill Tom JOE BILL TOM

Raw array data

Joe Bill Tom JOE BILL TOM

Natural order sorted array data

BILL Bill JOE Joe TOM Tom

Custom order sorted array data

Tom TOM Joe JOE Bill BILL

Collection data

Joe Bill Tom JOE BILL TOM

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Answer 3

True.

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Answer 2

True.

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Answer 1

False. The Collection interface declares a method named toArray , which can be called on a Collection object to "return an array containing all of the elements in this collection whose runtime type is that ofthe specified array" .