/**
   * Create a list of layers described by an array of XML layer description elements.
   *
   * <p>Any exceptions occurring during creation of the layers are logged and not re-thrown. The
   * layers associated with the exceptions are not included in the returned layer list.
   *
   * @param layerElements the XML elements describing the layers to create.
   * @param params any parameters to apply when creating the layers.
   * @return a layer list containing the specified layers.
   */
  protected LayerList createLayerList(Element[] layerElements, AVList params) {
    LayerList layerList = new LayerList();

    for (Element element : layerElements) {
      try {
        layerList.add(this.createFromLayerDocument(element, params));
      } catch (Exception e) {
        Logging.logger().log(java.util.logging.Level.WARNING, e.getMessage(), e);
        // keep going to create other layers
      }
    }

    return layerList;
  }
  /**
   * Create a collection of layer lists and their included layers described by an array of XML
   * layer-list description elements.
   *
   * <p>Any exceptions occurring during creation of the layer lists or their included layers are
   * logged and not re-thrown. The layers associated with the exceptions are not included in the
   * returned layer list.
   *
   * @param elements the XML elements describing the layer lists to create.
   * @param params any parameters to apply when creating the included layers.
   * @return an array containing the specified layer lists.
   */
  protected LayerList[] createLayerLists(Element[] elements, AVList params) {
    ArrayList<LayerList> layerLists = new ArrayList<LayerList>();

    for (Element element : elements) {
      try {
        String href = WWXML.getText(element, "@href");
        if (href != null && href.length() > 0) {
          Object o = this.createFromConfigSource(href, params);
          if (o == null) continue;

          if (o instanceof Layer) {
            LayerList ll = new LayerList();
            ll.add((Layer) o);
            o = ll;
          }

          if (o instanceof LayerList) {
            LayerList list = (LayerList) o;
            if (list != null && list.size() > 0) layerLists.add(list);
          } else if (o instanceof LayerList[]) {
            LayerList[] lists = (LayerList[]) o;
            if (lists != null && lists.length > 0) layerLists.addAll(Arrays.asList(lists));
          } else {
            String msg =
                Logging.getMessage("LayerFactory.UnexpectedTypeForLayer", o.getClass().getName());
            Logging.logger().log(java.util.logging.Level.WARNING, msg);
          }

          continue;
        }

        String title = WWXML.getText(element, "@title");
        Element[] children = WWXML.getElements(element, "./Layer", null);
        if (children != null && children.length > 0) {
          LayerList list = this.createLayerList(children, params);
          if (list != null && list.size() > 0) {
            layerLists.add(list);
            if (title != null && title.length() > 0) list.setValue(AVKey.DISPLAY_NAME, title);
          }
        }
      } catch (Exception e) {
        Logging.logger().log(java.util.logging.Level.WARNING, e.getMessage(), e);
        // keep going to create other layers
      }
    }

    return layerLists.toArray(new LayerList[layerLists.size()]);
  }