数据被添加到列表中，而不是在 addChildEventListener 的 onChildChanged() 中更新 [英] Data is getting added into list instead of getting updated in addChildEventListener's onChildChanged()
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问题描述
我在 firebase 中有一些数据会在某些特定操作上发生更改，我希望该更改显示在应用中.
I have some data in firebase which gets changed on some specific actions and I want that change to be shown in the app.
我有一个 RecyclerView，其中填充了来自 firebase 的所有数据.
I have a RecyclerView in which all the data from firebase is getting populated.
代码如下:
databaseReference.child("uListings").child(AccessToken.getCurrentAccessToken().getUserId()).addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
// recyclerview gets populated here
}
@Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
if (dataSnapshot.getValue() != null) {
Map<String,String> map = (Map<String,String>)dataSnapshot.getValue();
Map<ArrayList<String>,ArrayList<String>> map2 = (Map<ArrayList<String>,ArrayList<String>>)dataSnapshot.getValue();
String pDescription = map.get("pDescription");
String pDuration = map.get("pDuration");
String pPrice = map.get("pPrice");
String postedAt = map.get("postedAt");
String views = map.get("views");
ArrayList<String> imageUrl = map2.get("imageUrl");
if (imageUrl != null) {
UHandler pHandler = new UHandler(imageUrl.get(0), pDescription, pDuration, pPrice, postedAt, views);
list.add(pHandler);
adapter.notifyDataSetChanged();
progressBar.setVisibility(View.INVISIBLE);
} else {
Toast.makeText(getBaseContext(), "imageUrlNone", Toast.LENGTH_SHORT).show();
}
} else {
Log.d("PDPchange", "NULL");
progressBar.setVisibility(View.INVISIBLE);
}
}
@Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
@Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
这是UHandlerAdapter.java:
public class UHandlerAdapter extends RecyclerView.Adapter<UHandlerAdapter.MyViewHolder> {
private Context mContext;
private List<UHandler> listingList;
public class MyViewHolder extends RecyclerView.ViewHolder {
public TextView pDescription, pDuration, pPrice, postedAt, listingViews, imageUrl;
public ArrayList<String> imageUrls;
public CircleImageView pImage;
public MyViewHolder(View view) {
super(view);
pImage = (CircleImageView) view.findViewById(R.id.p_image_profile);
pDescription = (TextView) view.findViewById(R.id.p_description_profile);
pDuration = (TextView) view.findViewById(R.id.p_duration_profile);
pPrice = (TextView) view.findViewById(R.id.p_price_profile);
postedAt = (TextView) view.findViewById(R.id.p_posted_when_profile);
listingViews = (TextView) view.findViewById(R.id.listing_views_profile);
imageUrl = (TextView) view.findViewById(R.id.image_urls_profile);
}
}
public UHandlerAdapter(Context mContext, List<UProfileHandler> listingList) {
this.mContext = mContext;
this.listingList = listingList;
}
@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext())
.inflate(R.layout.profile_all, parent, false);
return new MyViewHolder(itemView);
}
@Override
public void onBindViewHolder(final MyViewHolder holder, int position) {
UHandler handler = listingList.get(position);
holder.pDescription.setText(handler.getPDescriptionProfile());
holder.pDuration.setText(handler.getPDurationProfile());
holder.pPrice.setText(handler.getPPriceProfile());
holder.postedAt.setText(handler.getPostedAt());
holder.listingViews.setText(handler.getListingViews());
// loading album cover using Glide library
Glide.with(mContext)
.load(handler.getPImageProfile())
.apply(new RequestOptions().placeholder(R.drawable.ic_placeholder).error(R.drawable.ic_error))
.into(holder.pImage);
}
@Override
public int getItemCount() {
return listingList.size();
}
}
问题在于，在 onChildChanged() 中，被更改的 views 在列表中添加了一个完整的其他项目，反映了它的更改值，而不仅仅是在之前添加的内容中更新onChildAdded() 中的项目.
The problem is that in onChildChanged() the views which gets changed add a complete other item in the list reflecting it's changed value and not just gets updated in previously added items in onChildAdded().
我怎样才能在之前添加的项目本身中更新它?
How can I just update it in the previously added items itself?
推荐答案
您可以存储 keys 以更新它，例如:
You can store keys in order to update it e.g:
ArrayList<String> mKeys = new ArrayList<String>();
databaseReference.child("uListings").child(AccessToken.getCurrentAccessToken().getUserId()).addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
// recyclerview gets populated here
String key = dataSnapshot.getKey();
mKeys.add(key);
adapter.notifyDataSetChanged();
}
@Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
if (dataSnapshot.getValue() != null) {
.......
//now we get the index to update specific value
String key = dataSnapshot.getKey();
int index = mKeys.indexOf(key);
list.set(index, pHandler);
adapter.notifyDataSetChanged();
....
}
这篇关于数据被添加到列表中，而不是在 addChildEventListener 的 onChildChanged() 中更新的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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