Lesson 18 : The Radio Button

The radio button is another control in Visual Basic 2010 that allows selection of choices. However, it operates differently from the check box. While the check boxes allow the user to select one or more items, radio buttons are mutually exclusive, which means the user can only choose one item only out of a number of choices. Here is an example which allows the user to select one color only, as shown in Figure 18.1.

The Code

Dim strColor As String

Private Sub RadioButton8_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioButton8.CheckedChanged
 strColor = "Red"
End Sub

Private Sub RadioButton7_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioButton7.CheckedChanged
 strColor = "Green"
End Sub

Private Sub RadioYellow_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioYellow.CheckedChanged
 strColor = "Yellow"
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
 Label2.Text = strColor
End Sub

Although the user may only select one item at a time, he may make more than one selection if those items belong to different categories. For example, the user wishes to choose T-shirt size and color, he needs to select one color and one size, which means one selection in each category. This is easily achieved in Visual Basic 2010 by using the Groupbox control under the containers categories. After inserting the Groupbox into the form, you can proceed to insert the radio buttons into the Groupbox. Only the radio buttons inside the Groupbox are mutually exclusive, they are not mutually exclusive with the radio buttons outside the Groupbox. In Example 18.2, the user can select one color and one size of the T-shirt.

Example 18.2

The code

Dim strColor As String
Dim strSize As String

Private Sub RadioButton8_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioButton8.CheckedChanged
 strColor = "Red"
End Sub

Private Sub RadioButton7_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioButton7.CheckedChanged
 strColor = "Green"
End Sub

Private Sub RadioYellow_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioYellow.CheckedChanged
 strColor = "Yellow"
End Sub

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
 Label2.Text = strColor
 Label4.Text = strSize
End Sub

Private Sub RadioXL_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles 
RadioXL.CheckedChanged
 strSize = "XL"
End Sub

Private Sub RadioL_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioL.CheckedChanged
 strSize = "L"
End Sub

Private Sub RadioM_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioM.CheckedChanged
 strSize = "M"
End Sub

Private Sub RadioS_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioS.CheckedChanged
 strSize = "S"
End Sub