1. Fundamentals of Programming in VB.Net
VB.NET Events
An Event Procedure Walkthrough
Properties and Event Procedures of the Form
The Declaration Statement of an Event Procedure
2/24/2019
Fundamentals of Programming in VB.Net

2. Fundamentals of Programming in VB.Net
What is an event?
An event is an action, such as the user clicking on a button
Usually, nothing happens until the user does something and generates an event
2/24/2019
Fundamentals of Programming in VB.Net

3. Fundamentals of Programming in VB.Net
VB.NET program:
Create the interface; that is, generate, position, and size the objects.
Set properties; that is, configure the appearance of the objects.
Write the code that executes when events occur. This block of code is called event procedure.
2/24/2019
Fundamentals of Programming in VB.Net

4. Fundamentals of Programming in VB.Net
Event Procedures
Private Sub objectName_event(
ByVal sender As System.Object,
ByVal e As System.EventArgs)
Handles objectName.event
statements
End Sub
Private Sub ObjectName_event(…) Handles objectName.event
Because the book does not make use of the parameter list, it is replaced with an ellipsis
2/24/2019
Fundamentals of Programming in VB.Net

5. Fundamentals of Programming in VB.Net
Statements
Properties of controls can be changed both in the Properties window and in the statements of the event procedure.
The statement we use to change the property value is call an Assignment statement
2/24/2019
Fundamentals of Programming in VB.Net

6. Fundamentals of Programming in VB.Net
Changing Properties
Properties are changed in code with the following:
controlName.property = setting
This is an assignment statement
txtBox.ForeColor = Color.Red
Me.Text = "Demonstration“
Instead of
(VB.6) Form1.Text = "Demonstration"
The form is referred to by the keyword Me.
The setting value on the right hand side of the equal sign is being assigned to the property of the control listed on the left hand side of the equal sign
2/24/2019
Fundamentals of Programming in VB.Net

7. Fundamentals of Programming in VB.Net
Program Region
2/24/2019
Fundamentals of Programming in VB.Net

8. Dropdown Boxes Automatically pops up to give the programmer help.
2/24/2019
Fundamentals of Programming in VB.Net

9. Fundamentals of Programming in VB.Net
Help
Help menu
Press ALT/H/I - Help index window
Dynamic help – samples
(Member Listing)
Type dot “.” following a word
Type parenthesis following a word
Context-sensitive help
Place cursor on the word, and press F1
2/24/2019
Fundamentals of Programming in VB.Net

10. Fundamentals of Programming in VB.Net
Event Outcomes
Private Sub txtFirst_TextChanged(...)
Handles txtFirst.TextChanged
txtFirst.ForeColor = Color.Blue
End Sub
Private Sub btnRed_Click(...)
Handles btnRed.Click
txtFirst.ForeColor = Color.Red
Private Sub txtFirst_Leave(...)
Handles txtFirst.Leave
txtFirst.ForeColor = Color.Black
2/24/2019
Fundamentals of Programming in VB.Net

11. The Declaration Statement of an Event Procedure
A declaration statement for an event procedure:
Private Sub btnOne_Click(...)
Handles btnOne.Click
The name can be changed at will.
Private Sub ButtonPushed(...)
Handling more than one event:
Handles btnOne.Click, btnTwo.Click
btnOne_Click is the name of the event procedure, and btnOne.Click identifies the
event that triggers the procedure
Also, an event procedure can be triggered by more than one event.
2/24/2019
Fundamentals of Programming in VB.Net