How to: Detect RadioButton Selections

When RadioButton controls are grouped, the buttons are mutually exclusive. A user can select only one item at a time within a RadioButton group. The application programmatically clears a selected item when the user selects a new item. Whether a RadioButton is selected is determined by the state of its IsChecked property. You can group RadioButton controls by placing them inside a parent or by giving them a group name. The following code example does both; the RadioButton controls are the child elements of a StackPanel, and the group name is ExpandDirectionProperty.

When a RadioButton is selected, the Checked event is raised. As the following code example shows, if your application needs to take some action when the RadioButton selection changes, you can add an event handler to handle the Checked event.

Example

<StackPanel>
  <RadioButton Name="ExpandDown" Margin="0,10,0,10" 
            IsChecked="True"
            Checked="ChangeExpandDirection"
            GroupName="ExpandDirectionProperty">
     Expand Down
  </RadioButton>
  <RadioButton Name="ExpandUp" Margin="0,0,0,10"
            Checked="ChangeExpandDirection"
            GroupName="ExpandDirectionProperty">
     Expand Up
  </RadioButton>
  <RadioButton Name="ExpandLeft" Margin="0,0,0,10"
            Checked="ChangeExpandDirection"
            GroupName="ExpandDirectionProperty">
    Expand Left
  </RadioButton>
  <RadioButton Name="ExpandRight" Margin="0,0,0,10"
            Checked="ChangeExpandDirection"
            GroupName="ExpandDirectionProperty">
    Expand Right
  </RadioButton>
</StackPanel>

Private Sub ChangeExpandDirection(ByVal Sender As Object, ByVal e As RoutedEventArgs)
    If (ExpandDown.IsChecked) Then
        myExpander.ExpandDirection = ExpandDirection.Down
    ElseIf (ExpandUp.IsChecked) Then
        myExpander.ExpandDirection = ExpandDirection.Up
    ElseIf (ExpandLeft.IsChecked) Then
        myExpander.ExpandDirection = ExpandDirection.Left
    ElseIf (ExpandRight.IsChecked) Then
        myExpander.ExpandDirection = ExpandDirection.Right
    End If 

    'Expand myExpander so it is easier to see the effect of changing  
    'the ExpandDirection property for My Expander
    myExpander.IsExpanded = True 
End Sub

private void ChangeExpandDirection(object sender, RoutedEventArgs e)
{
    if ((Boolean)ExpandDown.IsChecked)
        myExpander.ExpandDirection = ExpandDirection.Down;
    else if ((Boolean)ExpandUp.IsChecked)
        myExpander.ExpandDirection = ExpandDirection.Up;
    else if ((Boolean)ExpandLeft.IsChecked)
        myExpander.ExpandDirection = ExpandDirection.Left;
    else if ((Boolean)ExpandRight.IsChecked)
        myExpander.ExpandDirection = ExpandDirection.Right;

    //Expand myExpander so it is easier to see the effect of changing  
    //the ExpandDirection property for My Expander
    myExpander.IsExpanded = true;
}