How can I use Tasks with Firestore onSnapshotListener?

Question

I want to update real time data in my app. I have changed the code but problem is Task Cannot Find .

private void getData() {
    showProgressDialog();
    Query query;
    if (islast) {
        query = db.collection(node)
                .document(lastid)
                .collection("list")
                .document(id)
                .collection("list");
    } else {
        query = db.collection(node)
                .document(id)
                .collection("list");
    }

    query.addSnapshotListener(new EventListener<QuerySnapshot>() {
        @Override
        public void onEvent(@Nullable QuerySnapshot value, @Nullable FirebaseFirestoreException error) {

                    dismissProgressDialog();
                    if (task.isSuccessful()) {

                        list.clear();
                        int i = 0;
                        boolean match = false;
                        try {
                            for (DocumentSnapshot snapshot : task.getResult().getDocuments()) {
                                CardModel mainModel = snapshot.toObject(CardModel.class);
                                mainModel.setId(snapshot.getId());
                                if (mainModel.enable) {
                                    boolean onOff=mainModel.cOnOff;
                                    if (mainModel.countries != null
                                            && mainModel.countries.size() > 0) {
                                        if (!sessionManager.getLocation().isEmpty()) {
                                            if(onOff) {
                                                if (mainModel.countries.contains(sessionManager.getLocation())) {
                                                    match = true;
                                                    list.add(mainModel);
                                                } else {
                                                    list.remove(mainModel);
                                                }

                                            }else{
                                                if (mainModel.countries.contains(sessionManager.getLocation())) {
                                                    match = true;
                                                    list.remove(mainModel);
                                                } else {
                                                    list.add(mainModel);
                                                }
                                            }
                                        } else {
                                            list.add(mainModel);
                                        }
                                    } else {
                                        list.add(mainModel);
                                    }
                                } else {
                                    list.remove(mainModel);
                                }
                                Log.d("view imgs", "data is " + mainModel.toString());

                            }
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                        adapter.notifyDataSetChanged();

                    }
                    adapter.notifyDataSetChanged();
                    dismissProgressDialog();
                }
            })
            .addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception e) {
                  dismissProgressDialog();
                    Toast.makeText(Category_List_Activity.this, e.getMessage(), Toast.LENGTH_SHORT).show();
                }
            })
    ;
}

my old code... sir can u Get realtime updates with Cloud Firestore? this code isn't working in realtime.. it works only whenever i restart/refresh the app. i am using cloud Firestore. my java is not good please sir u change this code in real-time...

   private void getData() {
        showProgressDialog();
        Query query;
        if (islast) {
            query = db.collection(node)
                    .document(lastid)
                    .collection("list")
                    .document(id)
                    .collection("list");
        } else {
            query = db.collection(node)
                    .document(id)
                    .collection("list");
        }

        query.get()
                .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                    @Override
                    public void onComplete(@NonNull Task<QuerySnapshot> task) {
                        dismissProgressDialog();
                        if (task.isSuccessful()) {

                            list.clear();
                            int i = 0;
                            boolean match = false;
                            try {
                                for (DocumentSnapshot snapshot : task.getResult().getDocuments()) {
                                    CardModel mainModel = snapshot.toObject(CardModel.class);
                                    mainModel.setId(snapshot.getId());
                                    if (mainModel.enable) {
                                        boolean onOff=mainModel.cOnOff;
                                        if (mainModel.countries != null
                                                && mainModel.countries.size() > 0) {
                                            if (!sessionManager.getLocation().isEmpty()) {
                                                if(onOff) {
                                                    if (mainModel.countries.contains(sessionManager.getLocation())) {
                                                        match = true;
                                                        list.add(mainModel);
                                                    } else {
                                                        list.remove(mainModel);
                                                    }

                                                }else{
                                                    if (mainModel.countries.contains(sessionManager.getLocation())) {
                                                        match = true;
                                                        list.remove(mainModel);
                                                    } else {
                                                        list.add(mainModel);
                                                    }
                                                }
                                            } else {
                                                list.add(mainModel);
                                            }
                                        } else {
                                            list.add(mainModel);
                                        }
                                    } else {
                                        list.remove(mainModel);
                                    }
                                    Log.d("view imgs", "data is " + mainModel.toString());

                                }
                            } catch (Exception e) {
                                e.printStackTrace();
                            }
                            adapter.notifyDataSetChanged();

                        }
                        adapter.notifyDataSetChanged();
                        dismissProgressDialog();
                    }
                })
                .addOnFailureListener(new OnFailureListener() {
                    @Override
                    public void onFailure(@NonNull Exception e) {
                      dismissProgressDialog();
                        Toast.makeText(Category_List_Activity.this, e.getMessage(), Toast.LENGTH_SHORT).show();
                    }
                })
        ;
    }

Answer 1

Calling query.addSnapshotListener does not give you a task, but rather an event. The equivalent of your if (task.isSuccessful()) { within onEvent would be to check if (error == null) { , and the equivalent of addOnFailureListener would be to the else of the that condition.

If you really want to use a Task , you can call query.get instead of query.addSnapshotListener .