placementAssignment.setPlacementId(placementId);
PlacementAssignment[] placementAssignments = new PlacementAssignment[]{placementAssignment};
rotationGroup.setPlacementAssignments(placementAssignments);
// Save the rotation group.
AdSaveResult adSaveResult = service.saveAd(rotationGroup);
// Display the new ad ID.
System.out.printf("Ad with ID \"%s\" was created.%n", adSaveResult.getId());
}