Question 1

The UML distinguishes an interface from other classes by placing the word "interface" in above the interface name.

Accepted Answer

A)  italics.
B)  carets.
C)  guillemets.
D)  bold.

Question 2

Assigning a subclass reference to a superclass variable is safe:

Accepted Answer

A)  because the subclass object has an object of its superclass.
B)  because the subclass object is an object of its superclass.
C)  only when the superclass is abstract.
D)  only when the superclass is concrete.

Question 3

class cannot be instantiated.

Accepted Answer

A)  final.
B)  concrete.
C)  abstract.
D)  polymorphic. C

Question 4

When a superclass variable refers to a subclass object and a method is called on that object,the proper implementation is determined at execution time.What is the process of determining the correct method to call?

Accepted Answer

A)  early binding.
B)  non-binding.
C)  on-time binding.
D)  late binding.

Question 5

Which of the following is not possible?

Accepted Answer

A)  A class that implements two interfaces.
B)  A class that inherits from two classes.
C)  A class that inherits from one class,and implements an interface.
D)  All of the above are possible.

Question 6

Interfaces can have methods.

Accepted Answer

A)  0
B)  1
C)  2
D)  any number of

Question 7

Polymorphism enables you to:

Accepted Answer

A)  program in the general.
B)  program in the specific.
C)  absorb attributes and behavior from previous classes.
D)  hide information from the user.

Question 8

Classes and methods are declared final for all but the following reasons:

Accepted Answer

A)  final methods allow inlining the code.
B)  final methods and classes prevent further inheritance.
C)  final methods are static.
D)  final methods can improve performance.

Question 9

A class that implements an interface but does not declare all of the interface's methods must be declared:

Accepted Answer

A)  public.
B)  interface.
C)  abstract.
D)  final.

Question 10

Polymorphism allows for specifics to be dealt with during:

Accepted Answer

A)  execution.
B)  compilation.
C)  programming.
D)  debugging.

Question 11

Non-abstract classes are called:

Accepted Answer

A)  real classes.
B)  instance classes.
C)  implementable classes.
D)  concrete classes. D

Question 12

Declaring a method final means:

Accepted Answer

A)  it will prepare the object for garbage collection.
B)  it cannot be accessed from outside its class.
C)  it cannot be overloaded.
D)  it cannot be overridden.

Question 13

Every object in Java knows its own class and can access this information through method .

Accepted Answer

A)  getClass.
B)  getInformation.
C)  objectClass.
D)  objectInformation. A

Question 14

Which of the following does not complete the sentence correctly? An interface .

Accepted Answer

A)  forces classes that implement it to declare all the interface methods.
B)  can be used in place of an abstract class when there is no default implementation to inherit.
C)  is declared in a file by itself and is saved in a file with the same name as the interface followed by the .java extension.
D)  can be instantiated.

Question 15

It is a UML convention to denote the name of an abstract class in:

Accepted Answer

A)  bold.
B)  italics.
C)  a diamond.
D)  there is no convention of the UML to denote abstract classes-they are listed just as any other class.

Question 16

Which of the following statements about abstract superclasses is true?

Accepted Answer

A)  abstract superclasses may contain data.
B)  abstract superclasses may not contain implementations of methods.
C)  abstract superclasses must declare all methods as abstract.
D)  abstract superclasses must declare all data members not given values as abstract.

Question 17

Which statement best describes the relationship between superclass and subclass types?

Accepted Answer

A)  A subclass reference cannot be assigned to a superclass variable and a superclass reference cannot be assigned to a subclass variable.
B)  A subclass reference can be assigned to a superclass variable and a superclass reference can be assigned to a subclass variable.
C)  A superclass reference can be assigned to a subclass variable,but a subclass reference cannot be assigned to a superclass variable.
D)  A subclass reference can be assigned to a superclass variable,but a superclass reference cannot be assigned to a subclass variable.

Question 18

Which of the following could be used to declare abstract method method1 in abstract class Class1 (method1 returns an int and takes no arguments) ?

Accepted Answer

A)  public int method1() ;
B)  public int abstract method1() ;
C)  public abstract int method1() ;
D)  public int nonfinal method1() ;

Question 19

Consider classes A,B and C,where A is an abstract superclass,B is a concrete class that inherits from A and C is a concrete class that inherits from B.Class A declares abstract method originalMethod,implemented in class B.Which of the following statements is true of class C?

Accepted Answer

A)  Method originalMethod cannot be overridden in class C-once it has been implemented in concrete class B,it is implicitly final.
B)  Method originalMethod must be overridden in class C,or a syntax error will occur.
C)  If method originalMethod is not overridden in class C but is called by an object of class C,an error occurs.
D)  None of the above.

Question 20

All of the following methods are implicitly final except:

Accepted Answer

A)  a method in an abstract class.
B)  a private method.
C)  a method declared in a final class.
D)  static method.

Exam 10: Object-Oriented Programming: Polymorphism

The UML distinguishes an interface from other classes by placing the word "interface" in above the interface name.

Correct AnswerverifiedShow Answer

Assigning a subclass reference to a superclass variable is safe:

Correct AnswerverifiedShow Answer

class cannot be instantiated.

Correct AnswerverifiedC

When a superclass variable refers to a subclass object and a method is called on that object,the proper implementation is determined at execution time.What is the process of determining the correct method to call?

Correct AnswerverifiedShow Answer

Which of the following is not possible?

Correct AnswerverifiedShow Answer

Interfaces can have methods.

Correct AnswerverifiedShow Answer

Polymorphism enables you to:

Correct AnswerverifiedShow Answer

Classes and methods are declared final for all but the following reasons:

Correct AnswerverifiedShow Answer

A class that implements an interface but does not declare all of the interface's methods must be declared:

Correct AnswerverifiedShow Answer

Polymorphism allows for specifics to be dealt with during:

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Non-abstract classes are called:

Correct AnswerverifiedD

Declaring a method final means:

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Every object in Java knows its own class and can access this information through method .

Correct AnswerverifiedA

Which of the following does not complete the sentence correctly? An interface .

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It is a UML convention to denote the name of an abstract class in:

Correct AnswerverifiedShow Answer

Which of the following statements about abstract superclasses is true?

Correct AnswerverifiedShow Answer

Which statement best describes the relationship between superclass and subclass types?

Correct AnswerverifiedShow Answer

Which of the following could be used to declare abstract method method1 in abstract class Class1 (method1 returns an int and takes no arguments) ?

Correct AnswerverifiedShow Answer

Consider classes A,B and C,where A is an abstract superclass,B is a concrete class that inherits from A and C is a concrete class that inherits from B.Class A declares abstract method originalMethod,implemented in class B.Which of the following statements is true of class C?

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All of the following methods are implicitly final except:

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C

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D

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A

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