RecyclerView(FirestoreRecyclerOptions)显示为填充在活动的onCreate中，但当按

Question

请注意，我已将adapter.startListening()方法包含在我的onStart方法中：

public class Notifications extends AppCompatActivity {
private static final String TAG = "<< Notifications >>";
public static final String REQUEST_KEY = "notification request";
private NotificationAdapter notificationAdapter;
private RecyclerView notifyRecyclerview;
private Request request;
private Request notificationRequest;
private Query query;
private FirebaseAuth mAuth;
private FirebaseUser currentUser;
private FirebaseFirestore db = FirebaseFirestore.getInstance();
private CollectionReference requestsRef = db.collection("Users");
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_notifications);
//Firebase initialization
mAuth = FirebaseAuth.getInstance();
currentUser = mAuth.getCurrentUser();
Toolbar setup_toolbar = findViewById(R.id.notification_toolbar);
setup_toolbar.setTitle("Notifications");
setSupportActionBar(setup_toolbar);
if (getSupportActionBar() != null) {
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
}
// Recyclerview initialization
setupRecyclerview();
// An onclick listener for the individual clicked card
notificationAdapter.setOnItemCardClickListener(request -> {
Intent notifyIntent = new Intent(this, NotificationItem.class);
notifyIntent.putExtra(REQUEST_KEY, request);
startActivity(notifyIntent);
});
}
@Override
protected void onStart() {
super.onStart();
Log.d(TAG, "onStart: StartListening on the adapter");

//We must initialize listening to changes here
notificationAdapter.startListening();
}

@Override
protected void onStop() {
super.onStop();
Log.d(TAG, "onStop: StopListening");
//We must as well stop listening for changes when our app is in background to avoid resource wastage
notificationAdapter.stopListening();
}
private void setupRecyclerview() {
Log.d(TAG, "setupRecyclerview: ");
//Todo find a proper way to query the items per per the sort using latest item by current timestamp
query = requestsRef.document(currentUser.getUid()).collection("Requests").orderBy("date", Query.Direction.ASCENDING);
FirestoreRecyclerOptions<Request> options = new FirestoreRecyclerOptions.Builder<Request>()
.setQuery(query, Request.class)
.build();
notificationAdapter = new NotificationAdapter(options);
notifyRecyclerview = findViewById(R.id.notification_recy);
notifyRecyclerview.setHasFixedSize(true);
notifyRecyclerview.setLayoutManager(new LinearLayoutManager(this));
notifyRecyclerview.setAdapter(notificationAdapter);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
this.finish();
return true;
default:
return super.onOptionsItemSelected(item);
}
}
}

这是我的firebase firestore数据库子集合。我正在从用户集合/userID文档/请求集合查询数据库。然后从这里获取所有文档以填充我的回收视图

这是我的适配器活动。我在不同的适配器上使用了相同的实现，一切都很好，但我真的不明白为什么失败了

public class NotificationAdapter extends FirestoreRecyclerAdapter<Request, NotificationAdapter.NotificationViewHolder> {
Listener listener;
/**
* Create a new RecyclerView adapter that listens to a Firestore Query.  See {@link
* FirestoreRecyclerOptions} for configuration options.
*
* @param options
*/
public NotificationAdapter(@NonNull FirestoreRecyclerOptions<Request> options) {
super(options);
}
@NonNull
@Override
public NotificationViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
SingleNotificationItemBinding binding = DataBindingUtil.inflate(LayoutInflater.from(parent.getContext()),R.layout.single_notification_item,parent,false);
return new NotificationViewHolder(binding);
}
@Override
protected void onBindViewHolder(@NonNull NotificationViewHolder holder, int position, @NonNull Request model) {
holder.binding.setRequests(model);
holder.binding.notifyCardItem.setOnClickListener(v -> listener.onCardItemClick(model));
}
public void setOnItemCardClickListener(Listener listener){
this.listener = listener;
}
public interface Listener{
void onCardItemClick(Request request);
}
public class NotificationViewHolder extends RecyclerView.ViewHolder {
SingleNotificationItemBinding binding;
public NotificationViewHolder(@NonNull SingleNotificationItemBinding itemView) {
super(itemView.notifyCardItem);
this.binding = itemView;
}
}
}

Answer 1

我刚刚删除了setHasFixedSize(true(，它很有帮助！