Question 1

If a method needs to be called polymorphically,what type of reference should be used to point to the object that the method is being called with

Accepted Answer

A)  a reference of the base class that defines the behavior of the object 
B)  a reference of the same type as the object 
C)  an object reference to the actual object 
D)  None of the above. 
A)  a reference of the base class that defines the behavior of the object 
B)  a reference of the same type as the object 
C)  an object reference to the actual object 
D)  None of the above.

Question 2

Unfortunately,polymorphic programs make it difficult to add new capabilities to a system.

Accepted Answer

A) True 
 B)False

Question 3

The keyword sealed is applied to methods and classes to:

Accepted Answer

A)  prevent overriding and inheritance 
B)  guarantee an implementation exists 
C)  specify a class is concrete 
D)  None of the above. 
A)  prevent overriding and inheritance 
B)  guarantee an implementation exists 
C)  specify a class is concrete 
D)  None of the above.

Question 4

Classes and methods are declared sealed for all of the following reasons,except:

Accepted Answer

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

Question 5

Constants declared in an interface are implicitly _______.

Accepted Answer

A) private. 
B) static. 
C) abstract. 
D) All of the above. 
A) private. 
B) static. 
C) abstract. 
D) All of the above.

Question 6

You may define implementations for abstract methods to act as default implementations.

Accepted Answer

A) True 
 B)False

Question 7

Which of the following is false about interfaces

Accepted Answer

A)  An interface describes a set of methods that can be called on an object, providing a default implementation for the methods. 
B)  An interface describes a set of methods that can be called on an object, without providing concrete implementation for the methods. 
C)  Interfaces are useful when attempting to assign common functionality to possibly unrelated classes. 
D)  Once a class implements an interface, all objects of that class have an is-a relationship with the interface type. 
A)  An interface describes a set of methods that can be called on an object, providing a default implementation for the methods. 
B)  An interface describes a set of methods that can be called on an object, without providing concrete implementation for the methods. 
C)  Interfaces are useful when attempting to assign common functionality to possibly unrelated classes. 
D)  Once a class implements an interface, all objects of that class have an is-a relationship with the interface type.

Question 8

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

Question 9

If a derived class reference is assigned to a base class variable,the variable must be cast back to the derived class before any derived class methods can be called with it.

Accepted Answer

A) True 
 B)False

Question 10

Consider the abstract class below:
Public abstract class Foo
{
Private int a;
Public int b;
Public Foo(int aVal,int bVal)
{
A = aVal;
B = bVal;
}
Public abstract int calculate();
}
Any concrete subclass that extends class Foo:

Accepted Answer

A)  Must implement a method called calculate. 
B)  Will not be able to access the instance variable a. 
C)  Will not be able to instantiate an object of class Foo. 
D)  All of the above. 
A)  Must implement a method called calculate. 
B)  Will not be able to access the instance variable a. 
C)  Will not be able to instantiate an object of class Foo. 
D)  All of the above.

Question 11

When a request is made to use a derived-class-object method through a base-class reference,C# polymorphically chooses the correct overridden method in the appro
priate derived class that's associated with the object.

Accepted Answer

A) True 
 B)False

Question 12

By convention,the name for a Car interface is:

Accepted Answer

A)  InterfaceCar 
B)  ICar 
C)  CarI 
D)  None of the above. 
A)  InterfaceCar 
B)  ICar 
C)  CarI 
D)  None of the above.

Question 13

An interface reference may invoke only the methods that the interface declares.

Accepted Answer

A) True 
 B)False

Question 14

A class that implements an interface may not act as a base class for other classes.

Accepted Answer

A) True 
 B)False

Question 15

Which statement best describes the relationship between base class and derived class types

Accepted Answer

A) A derived class reference cannot be assigned to a base class variable and a base class
Reference cannot be assigned to a derived class variable. 
B) A derived class reference can be assigned to a base class variable and a base class
Reference can be assigned to a derived class variable. 
C) A base class reference can be assigned to a derived class variable,but a derived class
Reference cannot be assigned to a base class variable. 
D) A derived class reference can be assigned to a base class variable,but a base class
Reference cannot be assigned to a derived class variable. 
A) A derived class reference cannot be assigned to a base class variable and a base class
Reference cannot be assigned to a derived class variable. 
B) A derived class reference can be assigned to a base class variable and a base class
Reference can be assigned to a derived class variable. 
C) A base class reference can be assigned to a derived class variable,but a derived class
Reference cannot be assigned to a base class variable. 
D) A derived class reference can be assigned to a base class variable,but a base class
Reference cannot be assigned to a derived class variable.

Question 16

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. 
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 17

Polymorphism allows the addition of classes providing they were at least considered during program development.

Accepted Answer

A) True 
 B)False

Question 18

Polymorphism specifically enables the creation of programs that handle:

Accepted Answer

A)  classes that are containers for other classes 
B)  large amounts of data with efficiency 
C)  a wide variety of classes in a general manner 
D)  None of the above 
A)  classes that are containers for other classes 
B)  large amounts of data with efficiency 
C)  a wide variety of classes in a general manner 
D)  None of the above

Question 19

An abstract class cannot have instance data and non-abstract methods.

Accepted Answer

A) True 
 B)False

Question 20

Which of the following characteristics could be used to create an interface for a file,a cat and a house

Accepted Answer

A)  door 
B)  tail 
C)  age 
D)  None of the above. 
A)  door 
B)  tail 
C)  age 
D)  None of the above.

Exam 12: Object-Oriented Programming: Polymorphism

If a method needs to be called polymorphically,what type of reference should be used to point to the object that the method is being called with

Unfortunately,polymorphic programs make it difficult to add new capabilities to a system.

The keyword sealed is applied to methods and classes to:

Classes and methods are declared sealed for all of the following reasons,except:

Constants declared in an interface are implicitly _______.

You may define implementations for abstract methods to act as default implementations.

Which of the following is false about interfaces

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

If a derived class reference is assigned to a base class variable,the variable must be cast back to the derived class before any derived class methods can be called with it.

Consider the abstract class below: Public abstract class Foo { Private int a; Public int b; Public Foo(int aVal,int bVal) { A = aVal; B = bVal; } Public abstract int calculate(); } Any concrete subclass that extends class Foo:

When a request is made to use a derived-class-object method through a base-class reference,C# polymorphically chooses the correct overridden method in the appro priate derived class that's associated with the object.

By convention,the name for a Car interface is:

An interface reference may invoke only the methods that the interface declares.

A class that implements an interface may not act as a base class for other classes.

Which statement best describes the relationship between base class and derived class types

Polymorphism enables you to:

Polymorphism allows the addition of classes providing they were at least considered during program development.

Polymorphism specifically enables the creation of programs that handle:

An abstract class cannot have instance data and non-abstract methods.

Which of the following characteristics could be used to create an interface for a file,a cat and a house

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Introduction to C# Apps

Introduction to Classes,Objects,Methods and Strings

Control Statements: Part 1

Control Statements: Part 2

Methods: a Deeper Look

Arrays;Introduction to Exception Handling

Introduction to Linq and Generic Collections

Classes and Objects: A Deeper Look

Object-Oriented Programming: Inheritance

Exception Handling: A Deeper Look

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GUI With Windows Forms: Part 2

Strings,Characters and Regular Expressions

Files and Streams

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Asynchronous Programming With Async and Await

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