Sender
We have looked at the values of the argument e. Now we will look at the value of Sender and use it to improve our code.
Start a new project and name it Sender. Build the form as shown with the following buttons:
- BtnRed has a red background and the text is "Red"
- BtnBlue has a blue background and the text is "Blue"
- BtnGreen has a green background and the text is "Green"
Double click on BtnRed to open the code view window with BtnRed_Click selected. Change the name of the procedure to Button_Click and write the code as shown below:
Private Sub Button_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _
Handles BtnRed.Click, BtnGreen.Click, BtnBlue.Click
Me.BackColor = sender.backcolor
Me.Text = sender.text
End Sub
Run the program and click each button. The backcolor and text changes to match the button that was clicked.
Let's look at what is going on. First of all, notice the Handles clause after the arguments: instead of writing a procedure for each button, we are using one procedure and letting it handle the click event for each of the three buttons. The value of sender will be the button that was clicked.
Second, when we typed the code and typed sender dot, the list of properties for sender did not include backcolor and text. We had to type in the words backcolor and text ourselves.
If you know that Sender will be a button, you can change the type of sender to button by placing the cursor after As in ByVal sender As and type a space. The pop-up window will let you select Button as the type. Now when you type the dot after sender, the list will include all the properties of a button.
INDEX, The Code View, Selecting code from list, Events, Arguments, Concatenation, Sender, Scroll Bars, Decimal Values on Scroll Bar, Picture Boxes: the Seasons, Comments, Printing, Closing
Next lesson: Functions in Visual Basic
