在RecyclerView中选择并从java中的firebase中删除

Question

我想从firebase中删除我的文档。但首先我需要确定文档id。我试图获得文档id：

docId = queryDocumentSnapshots.getDocuments().get(pos).getId();

然后，我只想删除我的文档。但firebase是异步工作的，所以代码在"if"语句中不起作用。当我们第一次点击按钮时，docId变量为null，或者它采用之前点击的docId，直到异步代码部分完成。

@Override
public void onBindViewHolder(@NonNull AdvertisementHolder holder, int position) {
imgUrl = publishedAdvertisements.get(position).getImgUrl();
holder.petName.setText(publishedAdvertisements.get(position).getPetName());
holder.petCategory.setText(publishedAdvertisements.get(position).getPetCategory());
Picasso.get().load(publishedAdvertisements.get(position).getImgUrl()).into(holder.petImage);
holder.btnDelete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
firebaseFirestore = FirebaseFirestore.getInstance();
firebaseFirestore.collection("Pets").get().addOnSuccessListener(new OnSuccessListener<QuerySnapshot>() {
@Override
public void onSuccess(@NonNull QuerySnapshot queryDocumentSnapshots) {
if (!queryDocumentSnapshots.isEmpty()) {
System.out.println("bos döndü");
docId = queryDocumentSnapshots.getDocuments().get(pos).getId();
}
}
});

System.out.println(docId);
if (docId != null) {
FirebaseFirestore db = FirebaseFirestore.getInstance();
db.collection("Pets").document(docId)
.delete()
.addOnSuccessListener(new OnSuccessListener<Void>() {
@Override
public void onSuccess(Void aVoid) {
Log.d(TAG, "DocumentSnapshot successfully deleted!");
publishedAdvertisements.clear();
getPublishedAnimals();
}
})
.addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
Log.w(TAG, "Error deleting document", e);
}
});
}
notifyDataSetChanged();
}
});

Answer 1

您应该构建代码，以便在响应回调中执行或触发依赖于异步操作的任何逻辑。

你可以这样做：

@Override
public void onBindViewHolder(@NonNull AdvertisementHolder holder, int position) {
imgUrl = publishedAdvertisements.get(position).getImgUrl();
holder.petName.setText(publishedAdvertisements.get(position).getPetName());
holder.petCategory.setText(publishedAdvertisements.get(position).getPetCategory());
Picasso.get().load(publishedAdvertisements.get(position).getImgUrl()).into(holder.petImage);
holder.btnDelete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
firebaseFirestore = FirebaseFirestore.getInstance();
firebaseFirestore.collection("Pets").get().addOnSuccessListener(new OnSuccessListener<QuerySnapshot>() {
@Override
public void onSuccess(@NonNull QuerySnapshot queryDocumentSnapshots) {
// The asynchronous operation has successfully completed 
// and returned a value to our 'onSuccess()' callback.
if (!queryDocumentSnapshots.isEmpty()) {
System.out.println("bos döndü");
docId = queryDocumentSnapshots.getDocuments().get(pos).getId();

System.out.println(docId);
// We can now use the value of docId.
if (docId != null) {
FirebaseFirestore db = FirebaseFirestore.getInstance();
db.collection("Pets").document(docId)
.delete()
.addOnSuccessListener(new OnSuccessListener<Void>() {
@Override
public void onSuccess(Void aVoid) {
Log.d(TAG, "DocumentSnapshot successfully deleted!");
publishedAdvertisements.clear();
getPublishedAnimals();

// (1)
}
})
.addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
Log.w(TAG, "Error deleting document", e);
}
});
}

// I'm not sure how your RecyclerView is set up 
// but I'm guessing you might want to move this call
// to 'notifyDataSetChanged()' to the section marked (1)
notifyDataSetChanged();
}
}
});
}
});
}