4.5 Java4030r review  (Page 2/2)

Answer 12

Question 13

True or False? The Java documentation describes the general behavior that must be exhibited by each of the methods belonging to an object instantiated from a class that implements the Collection interface. This is sometimes referred to as a contract .

Answer 13

Question 14

True or False? If you define a class that implements the Collection interface in a manner consistent with the Collections Framework , you need not make certain that each of your methods behaves as described in theOracle documentation.

Answer 14

Question 15

True or False? A contract in the Collections Framework defines the behavior of declared methods in a very general way. There is noindication as to how that behavior is to be achieved.

Answer 15

Question 16

True or False? According to a contract of the Set interface, objects that implement the Set interface are allowed to contain duplicate elements.

Answer 16

Question 17

True or False? According to a contract of the Collection interface, objects that implement the Collection are never allowed to contain duplicate elements.

Answer 17

Question 18

True or False? The contract for the add method declared in the List interface, (which extends Collection) , does not prohibit duplicate elements.

Answer 18

Question 19

True or False? The List interface contract prohibits duplicate elements while the Set interface contract does not prohibit duplicate elements.

Answer 19

Question 20

True or False? The classes in the following list are concrete implementation classes in the Java Collections Framework:

• HashSet
• TreeSet
• LinkedList
• Vector
• ArrayList
• HashMap
• Hashtable
• WeakHashMap
• TreeMap

Answer 20

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.

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Answer 19

False. The Set interface contract prohibits duplicate elements while the List interface contract does not prohibit duplicate elements.

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Answer 18

True.

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Answer 17

False. The contract for the add method, as declared in the Collection interface, does not prohibit duplicate elements, but does make the provision for interfaces that extend Collection to prohibit duplicate elements. The contract for the add method in the Set interface does prohibit duplicate elements.

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Answer 16

False. According to a contract of the Set interface, objects that implement the Set interface never contain duplicate elements.

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Answer 15

True.

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Answer 14

False. If you define a class that implements the Collection interface in a manner consistent with the Collections Framework , you must make certain that each of your methods behaves as described in the Oracledocumentation. In other words, you must be careful to comply with the contract defined for those methods. If you don't do that, a user can't rely on objects instantiated from your class to exhibit proper behavior.

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Answer 13

True.

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Answer 12

True.

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Answer 11

False. there is no technical requirement for a specification of the behavior of the interface methods when implemented in a class. In fact, because a methodthat is declared in an interface is abstract, it specifically refrains from defining the behavior of the method. The interface definition simply declaresthe interfaces for all the methods that it declares.

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Answer 10

True.

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Answer 9

True.

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Answer 8

False. An object in Java can often be considered to be of several different types. One of those types is determined by any interfaces implemented by theclass from which the object was instantiated.

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Answer 7

True.

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Answer 6

True.

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Answer 5

True.

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Answer 4

False.

At least three things are included in a collections framework:

• interfaces
• implementations
• algorithms

Variables are not necessarily one of those things.

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Answer 3

False.

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Answer 2

True.

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Answer 1

True.

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Miscellaneous

This section contains a variety of miscellaneous information.

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