如何将 Tasks 与 Firestore onSnapshotListener 结合使用？

Question

我想在我的应用程序中更新实时数据。我已经更改了代码，但问题是 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();
                }
            })
    ;
}

我的旧代码...先生，您可以使用 Cloud Firestore 获取实时更新吗？此代码无法实时工作。它仅在我 restart/refresh 应用程序时有效。我正在使用云 Firestore。我的 java 不好请先生实时更改此代码...

   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

调用 query.addSnapshotListener 不会给你一个任务，而是一个事件。 onEvent 中的 if (task.isSuccessful()) { 相当于检查 if (error == null) {，而 addOnFailureListener 相当于该条件的 else。

如果你真的想使用 Task，你可以调用 query.get 而不是 query.addSnapshotListener。

如何将 Tasks 与 Firestore onSnapshotListener 结合使用？

How can I use Tasks with Firestore onSnapshotListener?

java

android

google-cloud-firestore