Deck 11: Classes and Objects

Question 1

____ are the actions to which an object can respond.

A) Attributes
B) Events
C) Behaviors
D) Methods

Answer 1

B

Question 2

You create a Public property using a ____.

A) Sub procedure
B) Function procedure
C) Property procedure
D) Set block

Answer 2

C

Question 3

You can overload any of the methods contained in a class.

Answer 3

True

Question 4

Private variables represent properties that will be seen by anyone using an object created from the class.

Question 5

A ____ encapsulates the attributes and behaviors of the object it creates.

A) constructor
B) property
C) class
D) structure

Question 6

When naming the Private variables in a class, many programmers use the ____ as the first character and then use camel case for the remainder of the name.

A) dash
B) admiration sign
C) asterisk
D) underscore

Question 7

Which of the following instantiates a Product object and assigns it to the bookcase variable?

A) Dim bookcase As Product
B) Dim bookcase As New Product
C) Dim Product As bookcase
D) Dim bookcase As String

Question 8

A Public property procedure creates a property that is visible to any application that contains an instance of the class.

Question 9

Only an instance of a class-not the class itself-is an object.

Question 10

Constructors never return a value, so they are always Function procedures.

Question 11

A class is anything that can be seen, touched, or used; in other words, a class is nearly any thing .

Question 12

In its simplest form, the Class statement can be used in place of the Structure statement.

Question 13

The purpose of a(n) ____ in OOP is to encapsulate the properties that describe an object, the methods that allow the object to perform tasks, and the events that allow the object to respond to actions.

A) event
B) class
C) method
D) attribute

Question 14

When a variable in a class is declared using the Public keyword, it can be used only within the class.

Question 15

In the following instruction, Room is a(n) ____. Dim bedroom As New Room

A) object
B) variable
C) class
D) property

Question 16

____ are the operations (actions) that the object is capable of performing.

A) Events
B) Attributes
C) Behaviors
D) Methods

Question 17

A one-dimensional array's Length property is an example of a ReadOnly property.

Question 18

Every object has ____, which are the characteristics that describe the object.

A) events
B) methods
C) attributes
D) behaviors

Question 19

The Class statement ends with the keyword(s) ____.

A) Class
B) Exit Class
C) End Class
D) Next Class

Question 20

A class can have multiple default constructors.

Question 21

A(n) ____ is a class method whose sole purpose is to initialize the class's Private variables.

A) signature
B) constructor
C) Get block
D) event

Question 22

____ is useful when two or more methods require different parameters to perform essentially the same task.

A) Instantiation
B) Overloading
C) Encapsulation
D) Overriding

Question 23

Constructors that contain parameters are called ____.

A) attributes
B) default constructors
C) Set blocks
D) parameterized constructors

Question 24

Case-Based Critical Thinking Questions Case 1 - chaussure.com
Chaussure.com is an online shoe retailer. The applications for the web site are developed using classes and object-oriented programming techniques.
Which of the following is a valid example of an object?

A) Place Order button in an application
B) credit card receipt
C) text box to enter the credit card number in an application
D) a and c
E) all of the above

Question 25

The code in the ____ allows an application to assign a value to the Private variable associated with the property.

A) Get block
B) default constructor
C) Set block
D) Property procedure

Question 26

You can create one class from another class. In OOP, this is referred to as ____.

A) encapsulation
B) overloading
C) overriding
D) inheritance

Question 27

A(n) ____ property gets its value from the class itself rather than from the application.

A) WriteOnly
B) ReadOnly
C) Set block
D) Get block

Question 28

When two or more methods have the same name but different parameters, the methods are referred to as ____.

A) default methods
B) parameterized methods
C) overloaded methods
D) Property procedures

Question 29

You indicate that a class is a derived class by including the ____ clause in the derived class's Class statement.

A) Inherits
B) Base
C) Overrides
D) Overloads

Question 30

Case-Based Critical Thinking Questions Case 1 - chaussure.com
Chaussure.com is an online shoe retailer. The applications for the web site are developed using classes and object-oriented programming techniques.
An application needs to calculate the sales tax for an order. Which of the following is a valid example of a variable in a class that can be validated in the Set block of a Property procedure?

A) Private TaxRate As Double
B) Private _dblTaxRate As Double
C) Public TaxRate As Double
D) Public _dblTaxRate As Double

Question 31

The first word in a method name should be a(n) ____.

A) verb
B) noun
C) adjective
D) preposition

Question 32

The Tree class is derived from a base class named Plant. Which of the following statements can be used by the Tree class to invoke the Plant class's default constructor?

A) MyPlant.New()
B) MyBase.New()
C) MyTree.New()
D) MyTree.Base

Question 33

A constructor that has no parameters is called the ____.

A) Property procedure
B) default constructor
C) parameterized constructor
D) Set block

Question 34

If you create an auto-implemented property named State, Visual Basic will create a hidden Private variable named ____.

A) State
B) _State
C) STATE
D) state_

Question 35

In a Property procedure, the dataType must match the data type of ____ associated with the Property procedure.

A) all constructors
B) all variables
C) the Public variable
D) the Private variable

Question 36

Which of the following clauses allows a derived class named Truck to have the same attributes and behaviors as its base class, which is named Automobile?

A) Inherit Truck
B) Inherits Truck
C) Inherit Automobile
D) Inherits Automobile

Question 37

The Inherits clause is the keyword ____ followed by the name of the class whose attributes and behaviors you want the derived class to inherit.

A) It Inherits
B) InheritsFrom
C) Inherits
D) Inherits_From

Question 38

In a Property procedure, the code contained in the ____ block allows an application to retrieve the contents of the Private variable associated with the property.

A) Set
B) Assign
C) New
D) Get

Question 39

A Property procedure begins with the keywords ____.

A) Public [ReadOnly | WriteOnly] Property
B) Private [ReadOnly | WriteOnly] Property
C) Start [ReadOnly | WriteOnly] Property
D) Dim [ReadOnly | WriteOnly] Property

Question 40

A method name combined with its optional parameterList is called the method's ____.

A) signature
B) event
C) attribute
D) behavior

Question 41

Explain the difference between Public and Private variables for a class.

Question 42

Case-Based Critical Thinking Questions Case 1 - chaussure.com
Chaussure.com is an online shoe retailer. The applications for the web site are developed using classes and object-oriented programming techniques.
Rather than reuse the Shoe class, you have decided to derive the Boot class from the Shoe class. Which of the following creates the derived Boot class?

A) Private Class Shoe Inherits Boot
B) Private Class Boot Inherits Shoe
C) Public Class Shoe Inherits Boot
D) Public Class Boot Inherits Shoe

Question 43

Problems - Correcting Logic and Code Errors
The following sample of code contains errors. Rewrite the incorrect statements to correct all errors.
Public Class Employee
Private _strEmpId As String
Public _decSalary As Decimal
Public Property EmpId As String
Set(ByVal value As String)
_strEmpId = value
End Set
End Property
Public Property Salary As Decimal
Get
Return _decSalary
End Get
Set(ByVal value As Decimal)
Salary = value
End Set
End Property
Public Function New()
_strEmpId = String.Empty
_decSalary = 0
End Sub
End Class

Question 44

Define the term "inheritance" in object-oriented programming and describe its use.

Question 45

Write a Class statement that defines a class named Employee. (The class contains four public variables named EmpID , LastName , FirstName , and PayRate . The EmpID , LastName , and FirstName variables are String variables. The PayRate variable is a Decimal variable.) Then write a statement that creates an Employee variable named partTime and also instantiates an Employee object, assigning it to the partTime variable.

Question 46

A base class named DeliveryFee contains a function named CalcFee that calculates an order's delivery fee using the following formula: total * .05. Write the method's procedure header in the base class that will allow the derived class to override the function.

Question 47

An application has a Private variable named _ decGPA . Write the statements for the Property procedure named GPA to validate the value received from the application before assigning it to the Private variable.

Question 48

The Lumber class definition contains two Private variables named _dblLength and _decPricePerFoot . The default constructor initializes the Private variables to 0 when the Lumber object is created. Write the statements to create a parameterized constructor, and then write the Dim statement using the parameterized constructor to instantiate and initialize the Lumber object where the number of feet of lumber is 31.5 and the price per foot is 1.85.

Question 49

Write a Class statement that defines a class named Furniture. The class contains two private variables named _strItemNum and   _dblPrice . Name the corresponding properties ItemNumber and Price.

Question 50

A base class named DeliveryFee contains a function named CalcFee that calculates an order's delivery fee using the following formula: total * .05. The derived class named InstallationFee contains the CalcFee method. However, the fee formula is as follows: ( total * .05) + 250. Write the function for the derived class.

Question 51

Problems - Correcting Logic and Code Errors
The following sample of code contains errors. Rewrite the incorrect statements to correct all errors.
Public Class Truck
Private Property Miles As Decimal
Public Function New()
_Miles = 0
End Function
Public Sub New(ByVal decM As Decimal)
Miles = decM
End Sub
Public Overrider Function GetMPG() As Decimal
'returns the miles per gallon for a truck
Return _Miles / 30
End Function
End Class
'derived class
Public Class Car
Receives Truck
Public Sub New()
MyBase.New()
End Sub
Public Sub New(ByVal decM As Decimal)
MyBase.New(decM)
End Sub
Public Function GetMPG() As Decimal
Return _Miles / 18
End Function
End Class

Question 52

Case-Based Critical Thinking Questions Case 1 - chaussure.com
Chaussure.com is an online shoe retailer. The applications for the web site are developed using classes and object-oriented programming techniques.
The Shoe class is used to create an object that represents a standard shoe. The Shoe class needs to be used in an application for boots. You have copied the Shoe.vb file into the boot application. What do you need to do next to include the file in the boot application?

A) Click PROJECT on the menu bar and then click Add Existing Item.
B) Select the Shoe.vb file from the list of filenames.
C) Click PROJECT on the menu bar and then click Add Class.
D) Click the Add button to add the file.

Question 53

Write the appropriate block of code to complete a Public procedure based on the following statements:
Private _decTotalSales As Decimal
Public WriteOnly Property TotalSales As Decimal
End Property

Question 54

Write the statements to create the default constructor for the Furniture class statement in the previous problem. Then write the Dim statement to use the default constructor to instantiate a Furniture object, assigning the object to a variable named sofa .

Question 55

Every object has attributes and behaviors. Describe each of these, including the two types of behaviors an object can have.

Question 56

What is a constructor? Explain the difference between a default constructor and a parameterized constructor.

Question 57

What is an auto-implemented property and what does it automatically create?

Question 58

Case-Based Critical Thinking Questions Case 1 - chaussure.com
Chaussure.com is an online shoe retailer. The applications for the web site are developed using classes and object-oriented programming techniques.
The Discount class is used by applications for assigning appropriate discounts to orders. A Public property within the class is made ReadOnly. Which of the following is true about this ReadOnly property?

A) The Set block of code will be entered in the class.
B) The applications using the Discount class will determine the appropriate discount.
C) The application will only be able to retrieve the discount.
D) The application will be able to change the discount.

Question 59

Write the code for an auto-implemented property named TaxableIncome. The property's data type is Decimal. Then list the two hidden items it creates.

Question 60

What are classes and objects? How are they used in object-oriented programming?