/**
   * 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()]);
  }
 public List<Tile> getTiles() {
   if (tileKeys.isEmpty()) {
     Tile[] tiles = buildTiles(this.placeNameService, this);
     // load tileKeys
     for (Tile t : tiles) {
       tileKeys.add(t.getFileCachePath());
       WorldWind.getMemoryCache(Tile.class.getName()).add(t.getFileCachePath(), t);
     }
     return Arrays.asList(tiles);
   } else {
     List<Tile> dataTiles = new ArrayList<Tile>();
     for (String s : tileKeys) {
       Tile t = (Tile) WorldWind.getMemoryCache(Tile.class.getName()).getObject(s);
       if (t != null) {
         dataTiles.add(t);
       }
     }
     return dataTiles;
   }
 }
  /**
   * Determines and stores the network sites to test for public network connectivity. The sites are
   * drawn from the JVM's gov.nasa.worldwind.avkey.NetworkStatusTestSites property ({@link
   * AVKey#NETWORK_STATUS_TEST_SITES}). If that property is not defined, the sites are drawn from
   * the same property in the World Wind or application configuration file. If the sites are not
   * specified there, the set of sites specified in {@link #DEFAULT_NETWORK_TEST_SITES} are used. To
   * indicate an empty list in the JVM property or configuration file property, specify an empty
   * site list, "".
   */
  protected void establishNetworkTestSites() {
    String testSites = System.getProperty(AVKey.NETWORK_STATUS_TEST_SITES);

    if (testSites == null)
      testSites = Configuration.getStringValue(AVKey.NETWORK_STATUS_TEST_SITES);

    if (testSites == null) {
      this.networkTestSites.addAll(Arrays.asList(DEFAULT_NETWORK_TEST_SITES));
    } else {
      String[] sites = testSites.split(",");
      List<String> actualSites = new ArrayList<String>(sites.length);

      for (String site : sites) {
        site = WWUtil.removeWhiteSpace(site);
        if (!WWUtil.isEmpty(site)) actualSites.add(site);
      }

      this.setNetworkTestSites(actualSites);
    }
  }