Zoom to Active Layer in TOC Snippet

///<summary>Zooms to the selected layer in the TOC associated with the active view.</summary>
/// 
///<param name="mxDocument">An IMxDocument interface</param>
///  
///<remarks></remarks>
public void ZoomToActiveLayerInTOC(ESRI.ArcGIS.ArcMapUI.IMxDocument mxDocument)
{
  if(mxDocument == null)
  {
    return;
  }
  ESRI.ArcGIS.Carto.IActiveView activeView = mxDocument.ActiveView; 

  // Get the TOC
  ESRI.ArcGIS.ArcMapUI.IContentsView IContentsView = mxDocument.CurrentContentsView;

  // Get the selected layer
  System.Object selectedItem = IContentsView.SelectedItem;
  if (!(selectedItem is ESRI.ArcGIS.Carto.ILayer))
  {
    return;
  }
  ESRI.ArcGIS.Carto.ILayer layer = selectedItem as ESRI.ArcGIS.Carto.ILayer; 


  // Zoom to the extent of the layer and refresh the map
  activeView.Extent = layer.AreaOfInterest;
  activeView.Refresh();
}

'''<summary>Zooms to the selected layer in the TOC associated with the active view.</summary>
''' 
'''<param name="mxDocument">An IMxDocument interface</param>
'''  
'''<remarks></remarks>
Public Sub ZoomToActiveLayerInTOC(ByVal mxDocument As ESRI.ArcGIS.ArcMapUI.IMxDocument)

  If mxDocument Is Nothing Then
    Return
  End If

  ' Get the map
  Dim activeView As ESRI.ArcGIS.Carto.IActiveView = mxDocument.ActiveView

  ' Get the TOC
  Dim contentsView As ESRI.ArcGIS.ArcMapUI.IContentsView = mxDocument.CurrentContentsView

  ' Get the selected layer
  Dim selectedItem As System.Object = contentsView.SelectedItem
  If Not (TypeOf selectedItem Is ESRI.ArcGIS.Carto.ILayer) Then
    Return
  End If

  Dim layer As ESRI.ArcGIS.Carto.ILayer = TryCast(selectedItem, ESRI.ArcGIS.Carto.ILayer) ' Dynamic Cast

  ' Zoom to the extent of the layer and refresh the map
  activeView.Extent = layer.AreaOfInterest
  activeView.Refresh()

End Sub