RadioButton
- The RadioButton control is used to display a radio button.
- RadioButtons are usually used in groups to allow the user to pick one from the group.
- All radioButtons in the same group must have the same groupName property
Property |
Description |
AutoPostBack |
A Boolean value that specifies whether the form should be posted immediately after the Checked property has changed or not. Default is false |
Checked |
A Boolean value that specifies whether the radio button is checked or not |
Id |
A unique id for the control |
GroupName |
The name of the group to which this radio button belongs |
OnCheckedChanged |
The name of the function to be executed when the Checked property has changed |
runat |
Specifies that the control is a server control. Must be set to "server" |
Text |
The text next to the radio button |
TextAlign |
On which side of the radio button the text should appear (right or left) |
1 |
<script runat="server"> |
2 |
Sub submit(Sender As Object, e As EventArgs) |
3 |
if red.Checked then |
4 |
Label1.Text="You selected " & red.Text |
5 |
elseIf green.Checked then |
6 |
Label1.Text="You selected " & green.Text |
7 |
elseIf blue.Checked then |
8 |
Label1.Text="You selected " & blue.Text |
9 |
end if |
10 |
End Sub |
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</script> |
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<html><body> |
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<form runat="server"> |
14 |
Select your favorite color: |
15 |
<br /> |
16 |
<asp:RadioButton id="red" Text="Red" Checked="True" GroupName="colors" runat="server"/> |
17 |
<br /> |
18 |
<asp:RadioButton id="green" Text="Green" GroupName="colors" runat="server"/> |
19 |
<br /> |
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<asp:RadioButton id="blue" Text="Blue" GroupName="colors" runat="server"/> |
21 |
<br /> |
22 |
<asp:Button text="Submit" OnClick="submit" runat="server"/> |
23 |
<p><asp:Label id="Label1" runat="server"/></p> |
24 |
</form> |
25 |
</body></html> |
Save as: RadioButton.aspx |
Determining if radioButton was checked:
If radioButtonName.checked then
‘do code if checked
End if
- Open Visual Studio
- Add a new webform
- Name it radioEx.aspx
- Click the Add button
- Select the Design View
- Add a label to the webform, change the text property to Select your favorite color. Change the id to lblPrompt
- Add an 3 radioButton controls to the webform
- Change the id of the radioButtons to red, green, blue
- Change the text of the radioButtons to Red,Green, Blue
- Set the autoPostBack property for all 3 radioButtons to true
- Press the control key and select each of the radioButton controls then change the groupName of all of them to Colors
- Change the checked property of the first radioButton to true
- Add another label below these controls and change the id to lblOutput, clear the text property
- Double-click the first radioButton
- Look at the subroutine signature:
Protected Sub red_CheckedChanged( ByVal sender As Object, ByVal e As System.EventArgs) Handles red.CheckedChanged
Visual Studio creates a subroutine and named it red_checkedChanged that handles the checkedChanged event of the red radioButton control
- Change the subroutine name to getChanged.
- Add a comma at the end and add green.checkedChanged
- Add another comma and add Blue.checkChanged
This will set this one subroutine to handle all 3 radioButton’s checkedChanged event
Protected Sub getChanged( ByVal sender As Object, ByVal e As System.EventArgs) Handles red.CheckedChanged, blue.CheckedChanged, Green.CheckedChanged
Add the following code to this subroutine:
If sender.Checked Then
lblOutput.Text = "You selected " & sender.Text
End If
Notice you are using the text from the sender object which will be passed into the subroutine
