Java 当数据从活动传递到片段时，片段中的RecycleView不显示任何内容

我有Firebase回收站的碎片视图。它很好用。 代码如下：

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view=inflater.inflate(R.layout.fragment_banknote_layout,container,false);

        //The next code is working on displaying all users coins per country
        banknotesList = (RecyclerView) view.findViewById(R.id.banknotes_list);
        banknotesList.setHasFixedSize(true);
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(view.getContext(), LinearLayoutManager.VERTICAL, false);
        linearLayoutManager.setReverseLayout(true);
        linearLayoutManager.setStackFromEnd(true);
        banknotesList.setLayoutManager(linearLayoutManager);

        DisplayAllCoins("russia");

        return view;
 }

    private void DisplayAllCoins(final String country_Key) {
        //Toast.makeText(getContext(), ""+country_Key, Toast.LENGTH_SHORT).show();
        final DatabaseReference coinsTotalRef = FirebaseDatabase.getInstance().getReference().child("admin").child("world_currency").child("year_title_data").child(country_Key);
        Query SortStoriesInDecendingOrder = coinsTotalRef.orderByChild("year_id");

        FirebaseRecyclerOptions<Banknotes> options =
                new FirebaseRecyclerOptions.Builder<Banknotes>()
                        .setQuery(SortStoriesInDecendingOrder, Banknotes.class)
                        .build();


        FirebaseRecyclerAdapter<Banknotes, BanknotesYearViewHolder> adapter =
                new FirebaseRecyclerAdapter<Banknotes, BanknotesYearViewHolder>(options) {
                    @Override
                    public void onBindViewHolder(@NonNull final BanknotesYearViewHolder viewHolder, int position, @NonNull Banknotes model) {
                        final String Year_Key = getRef(position).getKey();

                        viewHolder.setBanknote_year(model.getBanknote_year());
                        viewHolder.setCurrency(model.getCurrency());
                        viewHolder.setDenomination(model.getDenomination());
                        viewHolder.setComposition(model.getComposition());
                        viewHolder.setColor(model.getColor());
                    }

                    @NonNull
                    @Override
                    public BanknotesYearViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int viewType) {
                        View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.activity_world_currency_year_banknotes_data, viewGroup, false);
                        BanknotesYearViewHolder viewHolder = new BanknotesYearViewHolder(view);
                        return viewHolder;
                    }
                };
        banknotesList.setAdapter(adapter);
        adapter.startListening();


    }

现在我更新了片段代码：

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view=inflater.inflate(R.layout.fragment_banknote_layout,container,false);

        //The next code is working on displaying all users coins per country
        banknotesList = (RecyclerView) view.findViewById(R.id.banknotes_list);
        banknotesList.setHasFixedSize(true);
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(view.getContext(), LinearLayoutManager.VERTICAL, false);
        linearLayoutManager.setReverseLayout(true);
        linearLayoutManager.setStackFromEnd(true);
        banknotesList.setLayoutManager(linearLayoutManager);


        if(getArguments()!=null) {

            String country_Key = getArguments().getString("data").toLowerCase();
            DisplayAllCoins(country_Key);

        }
        

        return view;
 }

    private void DisplayAllCoins(final String country_Key) {
        Toast.makeText(getContext(), ""+country_Key, Toast.LENGTH_SHORT).show();
        final DatabaseReference coinsTotalRef = FirebaseDatabase.getInstance().getReference().child("admin").child("world_currency").child("year_title_data").child(country_Key);
        Query SortStoriesInDecendingOrder = coinsTotalRef.orderByChild("year_id");

        FirebaseRecyclerOptions<Banknotes> options =
                new FirebaseRecyclerOptions.Builder<Banknotes>()
                        .setQuery(SortStoriesInDecendingOrder, Banknotes.class)
                        .build();


        FirebaseRecyclerAdapter<Banknotes, BanknotesYearViewHolder> adapter =
                new FirebaseRecyclerAdapter<Banknotes, BanknotesYearViewHolder>(options) {
                    @Override
                    public void onBindViewHolder(@NonNull final BanknotesYearViewHolder viewHolder, int position, @NonNull Banknotes model) {
                        final String Year_Key = getRef(position).getKey();

                        viewHolder.setBanknote_year(model.getBanknote_year());
                        viewHolder.setCurrency(model.getCurrency());
                        viewHolder.setDenomination(model.getDenomination());
                        viewHolder.setComposition(model.getComposition());
                        viewHolder.setColor(model.getColor());
                    }

                    @NonNull
                    @Override
                    public BanknotesYearViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int viewType) {
                        View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.activity_world_currency_year_banknotes_data, viewGroup, false);
                        BanknotesYearViewHolder viewHolder = new BanknotesYearViewHolder(view);
                        return viewHolder;
                    }
                };
        banknotesList.setAdapter(adapter);
        adapter.startListening();


    }

@可空
@凌驾
创建视图时的公共视图（@NonNull LayoutInflater inflater、@Nullable ViewGroup container、@Nullable Bundle savedInstanceState）{
视图=充气机。充气（右布局。碎片\u钞票\u布局，容器，假）；
//下一个代码是显示每个国家的所有用户硬币
banknotesList=（RecyclerView）view.findViewById（R.id.banknotes\U列表）；
钞票列表。setHasFixedSize（真）；
LinearLayoutManager LinearLayoutManager=新的LinearLayoutManager（view.getContext（），LinearLayoutManager.VERTICAL，false）；
linearLayoutManager.setReverseLayout（true）；
linearLayoutManager.setStackFromEnd（true）；
钞票列表。setLayoutManager（linearLayoutManager）；
如果（getArguments（）！=null）{
字符串country_Key=getArguments（）.getString（“数据”）.toLowerCase（）；
显示所有硬币（国家/地区密钥）；
}
返回视图；
}
私有void DisplayAllCoins（最终字符串国家/地区密钥）{
Toast.makeText（getContext（），“”+country_键，Toast.LENGTH_SHORT）.show（）；
final DatabaseReference coinsTotalRef=FirebaseDatabase.getInstance（）.getReference（）.child（“管理”）.child（“世界货币”）.child（“年度标题数据”）.child（国家/地区密钥）；
查询SortStoriesInDecendingOrder=coinsTotalRef.orderByChild（“年份id”）；
FirebaseRecyclerOptions选项=
新的FirebaseRecyclerOptions.Builder（）
.setQuery（SortStoriesInDecendingOrder，Banknotes.class）
.build（）；
FirebaseRecyclerAdapter适配器=
新FirebaseRecyclerAdapter（选件）{
@凌驾
BindViewHolder上的公共无效（@NonNull final banksnotesyearViewholder viewHolder，int位置，@NonNull banks model）{
最终字符串年份_Key=getRef（位置）.getKey（）；
viewHolder.setBanknote_year（model.getBanknote_year（））；
viewHolder.setCurrency（model.getCurrency（））；
viewHolder.setDenomination（model.getDenomination（））；
setComposition（model.getComposition（））；
setColor（model.getColor（））；
}
@非空
@凌驾
公共钞票EarViewHolder onCreateViewHolder（@NonNull ViewGroup ViewGroup，int viewType）{
View View=LayoutInflater.from（viewGroup.getContext（））.flate（R.layout.activity\u world\u currency\u year\u banks\u data，viewGroup，false）；
BankNotesEarViewHolder viewHolder=新的BankNotesEarViewHolder（视图）；
返回视图持有者；
}
};
钞票列表设置适配器（适配器）；
adapter.startListening（）；
}

我正在使用Toast进行检查，我看到，参数“israel”已从另一个活动成功传递，但现在recycleView没有显示任何内容。。。。 有什么想法，为什么，我应该改变什么？

---

（如果我像以前一样编写“israel”硬编码，它会再次正常工作！）

Firebase数据库中是否存在键“israel”？听起来可能很明显，但如果Toast显示的是预期值，则表示错误在流中位于该值之后。当然。以色列存在于火场。如果我将写硬编码，它将工作良好！

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view=inflater.inflate(R.layout.fragment_banknote_layout,container,false);

        //The next code is working on displaying all users coins per country
        banknotesList = (RecyclerView) view.findViewById(R.id.banknotes_list);
        banknotesList.setHasFixedSize(true);
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(view.getContext(), LinearLayoutManager.VERTICAL, false);
        linearLayoutManager.setReverseLayout(true);
        linearLayoutManager.setStackFromEnd(true);
        banknotesList.setLayoutManager(linearLayoutManager);


        if(getArguments()!=null) {

            String country_Key = getArguments().getString("data").toLowerCase();
            DisplayAllCoins(country_Key);

        }
        

        return view;
 }

    private void DisplayAllCoins(final String country_Key) {
        Toast.makeText(getContext(), ""+country_Key, Toast.LENGTH_SHORT).show();
        final DatabaseReference coinsTotalRef = FirebaseDatabase.getInstance().getReference().child("admin").child("world_currency").child("year_title_data").child(country_Key);
        Query SortStoriesInDecendingOrder = coinsTotalRef.orderByChild("year_id");

        FirebaseRecyclerOptions<Banknotes> options =
                new FirebaseRecyclerOptions.Builder<Banknotes>()
                        .setQuery(SortStoriesInDecendingOrder, Banknotes.class)
                        .build();


        FirebaseRecyclerAdapter<Banknotes, BanknotesYearViewHolder> adapter =
                new FirebaseRecyclerAdapter<Banknotes, BanknotesYearViewHolder>(options) {
                    @Override
                    public void onBindViewHolder(@NonNull final BanknotesYearViewHolder viewHolder, int position, @NonNull Banknotes model) {
                        final String Year_Key = getRef(position).getKey();

                        viewHolder.setBanknote_year(model.getBanknote_year());
                        viewHolder.setCurrency(model.getCurrency());
                        viewHolder.setDenomination(model.getDenomination());
                        viewHolder.setComposition(model.getComposition());
                        viewHolder.setColor(model.getColor());
                    }

                    @NonNull
                    @Override
                    public BanknotesYearViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int viewType) {
                        View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.activity_world_currency_year_banknotes_data, viewGroup, false);
                        BanknotesYearViewHolder viewHolder = new BanknotesYearViewHolder(view);
                        return viewHolder;
                    }
                };
        banknotesList.setAdapter(adapter);
        adapter.startListening();


    }