调用类型列表的类方法时获取null

Question

我有以下api回复

"stories": [
       {
          "id": 754,
          "title": "what ever bla bla bla",

         - "feed": [
                     {
                      "feed_id": "2",
                      "title": "cnn",
                      "logo_url": "http://cnn.com/logo.gif",
                      "site_url": "http://cnn.com/"
                       }
                    ]
             }

代表这个我写了两个类：

 public class StoryAbstract {
      private long id;
      private String title;
 private List<Feeds> feed;
 ....
public List<Feeds> getFeeds() {
  return feed;
}

public void setFeeds(List<Feeds> feeds) {
  this.feed = feeds;
}

Feeds class：

public class Feeds {
       private long feed_id;
    private String title;
    private String logo_url;
    private String site_url;

    public Feeds(long feed_id, String title, String logo_url, String site_url) {
        this.feed_id = feed_id;
        this.title = title;
        this.logo_url = logo_url;
        this.site_url = site_url;
    }

    public long getFeed_id() {
        return feed_id;
    }

    public void setFeed_id(long feed_id) {
        this.feed_id = feed_id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getLogo_url() {
        return logo_url;
    }

    public void setLogo_url(String logo_url) {
        this.logo_url = logo_url;
    }

    public String getSite_url() {
        return site_url;
    }

    public void setSite_url(String site_url) {
        this.site_url = site_url;
    }
}

我试图在我的RecyclerView.ViewHolder中调用Feeds类的getTitle（）方法，但我得到空值

private static class ViewHolderItem extends RecyclerView.ViewHolder implements View.OnClickListener {

    private final TextView txtTitle;
    ...........        
    private StoryAbstract story;
    private Feeds feeds;
    private TextView feed_name;
    ....
  public void bindStory(StoryAbstract story) {
  this.story = story;
  txtTitle.setText(story.getTitle());
  ......
  feed_name.setText((CharSequence) feeds.getTitle());

我像这样调用bindStory：

  viewHolderItem.bindStory(storyList.get(position - 1));

其中storyList在故事适配器类中定义，如：

 private List<StoryAbstract> storyList;