从 Android 上的 Firebase Firestore 查询对象列表

Question

我正在尝试创建一种从我的Cloud Firestore database. 然后我会RecyclerView用上述列表设置一个适配器，它应该能很好地显示。截止目前，RecyclerView空空如也。（我还RecyclerView用虚拟项目测试了它们，它们显示得很好）在我的方法结束时，项目列表仍然是空的。日志以奇怪的顺序显示（最后一个日志显示在其他日志之前）。日志顺序让我怀疑在侦听器中运行了一些单独的线程。我不确定如何同步它们。private List<Project> projects;private FirebaseFirestore db;...在onCreateView()（我正在处理一个片段）： db = FirebaseFirestore.getInstance(); queryAllProjects(); recyclerView.setAdapter(new ProjectRecyclerViewAdapter(projects, ...... private void queryAllProjects() {        projects = new ArrayList<>();         //I've already tried to make a local list and return that, however,         //the compiler would force me to declare the list as final here, and it wouldn't solve anything.        db.collection("projects")                .get()                .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {                    @Override                    public void onComplete(@NonNull Task<QuerySnapshot> task) {                        if (task.isSuccessful()) {                            for (QueryDocumentSnapshot document : task.getResult()) {                                Log.d(TAG, document.getId() + " => " + document.getData());                                Project project = document.toObject(Project.class);                                projects.add(project);                            }                            Log.d(TAG, "After for loop: " + projects.toString());                             //Here the list is OK. Filled with projects.                             //I'd like to save the state of the list from here                        } else {                            Log.d(TAG, "Error getting document: ", task.getException());                            Toast.makeText(getContext(), R.string.error, Toast.LENGTH_SHORT).show();                        }                    }                });这是我一直在关注的官方文档https://firebase.google.com/docs/firestore/query-data/get-data#custom_objects

Answer 1

projects.add(project);

adapter.notifyDataSetChange()

添加列表后调用 notifyDataSetChange()