无法从reddit json结果中解析图像URL

Question

检查this for JSON DATA

我想解析preview -> images ->source -> url：

public class LChildData {

    @SerializedName("title")
    @Expose
    public String title;

    @SerializedName("preview")
    @Expose
    public LPreview preview;

}

public class LPreview {

    @SerializedName("images")
    @Expose
    public List<LImages> images =null;
}

public class LImages {

    @SerializedName("source")
    @Expose
    public LSource source;
}

public class LSource {

    @SerializedName("url")
    @Expose
    public String url;

}

ViewHolder代码：

 if (isValidImageUrl(holder.mItem.data.preview.images.get(0).source.url)) {
        Picasso.with(mContext)
                .load(holder.mItem.data.preview.images.get(0).source.url)
                .into(holder.mPostThumbnail);
    }

错误：

  

D / ViewAdapter：onBindViewHolder：image_url    ：https://i.redditmedia.com/RoARvRoBJHQihiWK_aHdhEZG2kabxNvmvY5kZKFkskk.jpg?s=037d08a057a7a6d253ab0937b6247353
  java.lang.NullPointerException：尝试调用虚方法    ＆＃39; java.util.List com.example.dex.redditclient.listings.model.LPreview.getImages（）＆＃39;在com.example.dex.redditclient.listings.ViewAdapter.onBindViewHolder（ViewAdapter.java:60）的null对象引用上