Chapter 7 : Class

Question 1

What is a class?

Answer 1

1. The blueprint for an object

Question 2

What does a class specifies ? ( 2 )

Answer 2

1. Fields
2. Methods

Question 3

What can be created from the class?

Answer 3

1. Object

Question 4

What does the objected created from a class called?

Answer 4

1. Instance of the class

Question 5

How to create a class?

Answer 5

class className
{
Member declaration(s)
}

Question 6

What is a constructor?

Answer 6

1. Special method automatically executed when an object is created

Question 7

How to create a object?

Answer 7

className objectName - new constructor

• Coin myCoin = new Coin();
• myCoin - Identifie that references an object of the Coin class
• new - creates an instance of the Coin class
• = - assigns the reference that was returend from the new operator to the myCoin identifie

Question 8

Where to create class? ( 2 )

Answer 8

1. Save the class declaration in a separate .cs file
2. Add it inside Form.cs file

Question 9

What is a property?

Answer 9

1. A class member that holds a piece of data about an object

Question 10

What is a backing field?

Answer 10

1. A variable that stores a value assigned to the property which the backing fields is associated with

Question 11

What is the access method of backing field?

Answer 11

1. private

• Protect it from accidental corruption

Question 12

What does it do when a backing vield is public?

Answer 12

1. Accessible directly by code outside the class without the need for accessors

Question 13

What does the get accessor do?

Answer 13

1. It is a method that returns the property’s value because it has a return statement

Question 14

What does the set accessor do?

Answer 14

1. It is a method gets the value stored in the backing field and assigns that value to the property

Question 15

When is get accessor executed?

Answer 15

1. It is executed whenever the property is read

• It has an implicit parameter named value

Question 16

When is set accessor is executed?

Answer 16

1. Whenever a value is assigned to the property

Question 17

What is a read-only property and how to set a read-only property?

Answer 17

1. A read-only property can be read, but it cannot be meodified
2. To ser a read-only property, simply do not write a set accessor for the property

Question 18

What is a parameterized constructor?

Answer 18

1. A constructor that accepts arguments

Question 19

What is overloaded methods?

Answer 19

1. Multiple versions of the same method

Question 20

How does the compiler know which method to call?

Answer 20

1. Relies on the signarutre of a method which consists of the methods’s name, the data type, and argument kind of the method’s parameter

Question 21

When is a method is overloaded?

Answer 21

1. Means that multiple methods in the same class have the same name but use different types of parameters

Question 22

Can constructors be overloaded?

Answer 22

1. Yes

• Compiler will find the matching constructor automatically
• public BankAccount() { } // parameterless constructor
  public BankAccount(decimal startingBalance) { } // overloaded
  public BankAccount(double startingBalance) { } // overloaded

Question 23

How to I identify the classes? ( 3 )

Answer 23

1. Get a written description of the problem domain
2. Identify all the nouns ( pronouns and noun phrases ) in the description . Each of these is a potential class
3. Refine the list to include only the class that are relavant to the problem

Question 24

What am I going to do once the class have been identified?

Answer 24

1. Identify each class’s responsibilities
   
   • The things that the class is responsible for knowing -> variable, arrary, list
   • The actions that the class is responsible for doing

Question 25

How to display a form?

Answer 25

ErrorForm myErrorForm = new ErrorForm(); myErrorForm.ShowDialog();

Question 26

How to access labelText from different class?

Answer 26

GreetingsForm greetingsForm = new GreetingForm(); greetingsForm.messageLabel.Text = "Good day!" greetingsForm.ShowDialog();

Question 27

What does a modal form do?

Answer 27

1. Must be closed or hidden before we can continue working with the rest of the application

Question 28

What does a modeless form do?

Answer 28

1. Allows the user to switch focus to another form while it is displayed * Does not have to close a modeless form to switch focus to another form

Question 29

What is the Flow of Executions for modal form?

Answer 29

1. Statement below ShowDialog method won't be execute until the modal form is closed statement; statement; messageForm.ShowDialog(); statement; statement; // not executed statement;

Question 30

What is the Flow of Executions of modeless form?

Answer 30

1. Statement below ShowDialog method will execute immediately after the modeless from is displayed statement; statement; messageForm.Show(); statement; statement; // executed statement;