anActor = ac.GetNextItem();
anActor = ac.GetNextActor();
public void keyPressed(KeyEvent e)  {    if (ren.VisibleActorCount() == 0) return;    char keyChar = e.getKeyChar();    if ('r' == keyChar)      {      ren.ResetCamera();      this.Render();      }    if ('u' == keyChar)      {      vtkPicker picker = new vtkPicker();      picker.Pick(lastX,700 - lastY,0.0,ren);      }    if ('w' == keyChar)      {      vtkActorCollection ac;      vtkActor anActor;      vtkActor aPart;      int i, j;                ac = ren.GetActors();      ac.InitTraversal();      for (i = 0; i < ac.GetNumberOfItems(); i++)	{	anActor = ac.GetNextItem();	anActor.InitPartTraversal();	for (j = 0; j < anActor.GetNumberOfParts(); j++)	  { 	  aPart = anActor.GetNextPart();	  aPart.GetProperty().SetRepresentationToWireframe();	  }	}      this.Render();      }    if ('s' == keyChar)      {      vtkActorCollection ac;      vtkActor anActor;      vtkActor aPart;      int i, j;                ac = ren.GetActors();      ac.InitTraversal();      for (i = 0; i < ac.GetNumberOfItems(); i++)	{	anActor = ac.GetNextItem();	anActor.InitPartTraversal();	for (j = 0; j < anActor.GetNumberOfParts(); j++)	  { 	  aPart = anActor.GetNextPart();	  aPart.GetProperty().SetRepresentationToSurface();	  }	}      this.Render();      }  }