code: public void setTileFactory(TileFactory fact)
      {
          mainMap.setTileFactory(fact);
          mainMap.setZoom(fact.getInfo().getDefaultZoomLevel());
          mainMap.setCenterPosition(new GeoPosition(0, 0));
          miniMap.setTileFactory(fact);
          miniMap.setZoom(fact.getInfo().getDefaultZoomLevel() + 3);
          miniMap.setCenterPosition(new GeoPosition(0, 0));
          zoomSlider.setMinimum(fact.getInfo().getMinimumZoomLevel());
          zoomSlider.setMaximum(fact.getInfo().getMaximumZoomLevel());
      }
docs: Sets the tile factory for both embedded JXMapViewer components. Calling this method will also reset the center
  and zoom levels of both maps, as well as the bounds of the zoom slider.
  @param fact the new TileFactory