android - 使用 Firestore UI 从 Firestore 检索数据并将其显示在 RecyclerView 中不适用于 API 24+

Question

在我的应用程序中有一个 Activity ，当它打开时它应该在 RecyclerView 中显示数据。数据存储在 Firestore 的一个集合中，但不幸的是它只适用于 API 21、22 和 23，上面的所有内容都没有显示数据(见屏幕截图)。有时它也不会在用户第一次打开 Activity 时显示数据，只有当他第二次打开它或注销并再次登录时(在 API 21 中)。这是已知的东西还是我的代码有问题？或者有没有更好的方法在 RecyclerView 中显示集合的数据？

我还注意到一个奇怪的行为:

当我在布局中添加一个 EditText 而没有在 Activity 中对其进行任何操作时，当用户单击 EditText 时，所需的文档就会按应有的方式显示。在运行 API 21 的模拟器上，无需单击 EditText 即可显示数据，因此上述行为适用于 API greater 24。有人可以解释此行为吗？

非常感谢任何帮助!

我遵循了本教程，一切正常:

https://www.youtube.com/watch?v=lAGI6jGS4vs

我的应用仅针对从 21 开始的 API。

这是我使用 RecyclerView 的 Activity :

public class PrizeGameActivity extends AppCompatActivity {

    private Toolbar mToolbar;

    private FirebaseFirestore db = FirebaseFirestore.getInstance();
    private CollectionReference prizesRef = db.collection("Prizes");

    private PrizeGameAdapter prizeGameAdapter;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_prize_game);

        // Sets the custom toolbar as ActionBar
        mToolbar = findViewById(R.id.toolbar);
        setSupportActionBar(mToolbar);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setDisplayShowTitleEnabled(false);

        setUpRecyclerView();
    }

    private void setUpRecyclerView() {

        Query query = prizesRef.orderBy("text",Query.Direction.ASCENDING);

        FirestoreRecyclerOptions<Prizes> options = new FirestoreRecyclerOptions.Builder<Prizes>()
                .setQuery(query, Prizes.class)
                .build();

        prizeGameAdapter = new PrizeGameAdapter(options);

        RecyclerView recyclerView = findViewById(R.id.recycler_view_prize_game);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setAdapter(prizeGameAdapter);

        prizeGameAdapter.startListening();
    }

    @Override
    protected void onStart() {
        super.onStart();
        if(prizeGameAdapter != null)
        {
            prizeGameAdapter.startListening();
        }
    }

    @Override
    protected void onStop() {
        super.onStop();
        if(prizeGameAdapter != null)
        {
            prizeGameAdapter.startListening();
        }
    }

    // Makes a left to right animation when user clicks the back button of the toolbar
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (item.getItemId() == android.R.id.home) {
            onBackPressed();
            return true;
        }
        return false;
    }

    // Makes a right left animation when clicking the back button
    @Override
    public void finish() {
        super.finish();
        overridePendingTransition(R.anim.slide_in_left, R.anim.slide_out_right);
    }
}

这是我的适配器:

public class PrizeGameAdapter extends FirestoreRecyclerAdapter<Prizes, PrizeGameAdapter.PrizeGameHolder> {

    public PrizeGameAdapter(@NonNull FirestoreRecyclerOptions<Prizes> options) {
        super(options);


    }

    @Override
    protected void onBindViewHolder(@NonNull PrizeGameHolder holder, int position, @NonNull Prizes model) {

        holder.textViewPrizeGame.setText(model.getText());

    }

    @NonNull
    @Override
    public PrizeGameHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.listitem_prize_game,parent, false);
        return new PrizeGameHolder(view);
    }

    class PrizeGameHolder extends RecyclerView.ViewHolder {

        TextView textViewPrizeGame;

        public PrizeGameHolder(@NonNull View itemView) {
            super(itemView);

            textViewPrizeGame = itemView.findViewById(R.id.listitem_text_view_prize_game);
        }
    }

}

这是我的奖品类:

public class Prizes {

    public Prizes (){

    }

    public String text;

    public String getText() {
        return text;
    }

    public void setText(String text) {
        this.text = text;
    }

    public Prizes(String text) {
        this.text = text;
    }
}

Answer 1

我设法通过添加 OnCompleteListener 并设置 RecyclerView 来获得所需的结果。这是代码:

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_prize_game);

        Query query = prizesRef.orderBy("text",Query.Direction.ASCENDING);

        FirestoreRecyclerOptions<Prizes> options = new FirestoreRecyclerOptions.Builder<Prizes>()
                .setQuery(query, Prizes.class)
                .build();

        prizeGameAdapter = new PrizeGameAdapter(options);

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

                }
            }
        });
    }

    private void setUpRecyclerView() {

        RecyclerView recyclerView = findViewById(R.id.recycler_view_prize_game);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setAdapter(prizeGameAdapter);

        prizeGameAdapter.startListening();
    }

    @Override
    protected void onStart() {
        super.onStart();
        if(prizeGameAdapter != null)
        {
            prizeGameAdapter.startListening();
        }
    }

    @Override
    protected void onStop() {
        super.onStop();
        if(prizeGameAdapter != null)
        {
            prizeGameAdapter.startListening();
        }
    }