Question

我有一个自定义列表适配器，它有许多查询数据库并将数据添加到不同java对象或列表的方法。

在适配器中考虑的代码如下： -

static class ViewHolder {
    ArrayList<String> imgUrls;

    //other variables;
}

然后在getView方法中将其启动为： -

public View getView(@params) {
    holder.imgUrls = new ArrayList<>();
}

//i have a method that query and retrieve data from firebase as follows:-
public void getPhoto(final ViewHolder holder) {
    Query query = reference
            .child(mContext.getString(R.string.dbname_collections))
            .child(holder.collection.getCollection_id())
            .child("photo_url");
    query.keepSynced(true);
    query.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            for (DataSnapshot singleSnapshot : dataSnapshot.getChildren()) {
                imgUrl = singleSnapshot.getValue(String.class);
                Log.d(TAG, "onDataChange: imgUrl: " + imgUrl);
                holder.imgUrls.add(imgUrl);
            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

    Log.d(TAG, "getPhoto: list with values " + holder.imgUrls);
}

我在firebase控制台中的数据库如下所示： -

{
  "collections": {
    "-L9nNSyF7ZhEqpvmPo0Z": {
      "caption": "jakhaha",
      "collection_id": "-L9nNSyF7ZhEqpvmPo0Z",
      "date_created": "2018-04-11T11:55:57Z",
      "photo_url": [
        "https://firebasestorage.googleapis.com/v0/b/backbench-72a47.appspot.com/o/collection%2Fusers%2FHb8ORoozQ3WhyxjaSyqazjHypkf2%2F2018-04-11T11%3A55%3A57Z%2Fphoto0?alt=media&token=08fdb740-9b16-455b-83ec-bfcec1455834",
        "https://firebasestorage.googleapis.com/v0/b/backbench-72a47.appspot.com/o/collection%2Fusers%2FHb8ORoozQ3WhyxjaSyqazjHypkf2%2F2018-04-11T11%3A55%3A57Z%2Fphoto1?alt=media&token=eeca4b10-0729-4ca9-be18-c31d054add19",
        "https://firebasestorage.googleapis.com/v0/b/backbench-72a47.appspot.com/o/collection%2Fusers%2FHb8ORoozQ3WhyxjaSyqazjHypkf2%2F2018-04-11T11%3A55%3A57Z%2Fphoto2?alt=media&token=b33c97b0-c2bf-4199-bef0-b498f505a678"
      ],
      //this are the imageUrls i want to retrieve as a arrylist
      "tags": "#NoTags",
      "user_id": "Hb8ORoozQ3WhyxjaSyqazjHypkf2"
    }
  }
}

在我的firebase模型类中： -

public class Collection implements Parcelable {

    //properties for photo (*case sensitive*)
    private String caption;
    private String date_created;
    private String collection_id;
    private String user_id;
    private String tags;
    //list of likes
    private List<String> photo_url;
    private List<Like> likes;
    private List<Comment> comments;

    public Collection() {

    }

    //constructor..getter setters etc...

}

在我的日志控制台中，我看到imgUrl的值是胖的

04-11 20:35:03.992 21269-21269/com.backbenchers.administrator.instaclone D/CollectionListAdapter: onDataChange: imgUrl://url of image 1
 onDataChange: imgUrl: url of image 2
    onDataChange: imgUrl: ...image 3

但它将列表显示为null或[]： -

D/CollectionListAdapter: getPhoto: list is with values : []

＆＃34;我想获取此firebase数据并将其添加到arraylist中。＆＃34;

有什么不对？

谢谢！

Android - 无法将数据添加到字符串的arraylist中 - 从firebase

0 个答案: