Java Firebase数据库：如何获取密钥并加入？

我想使用Firebases数据库中存储的数据创建一个重复的recycler视图，但问题是我必须加入，我不知道如何在我的情况下这样做

我希望获取请求者键值下的数据，并希望使用用户键值数据。我想做的是只在请求者用户id下查找，并获取数据全名和图像

也许它需要加入？我该怎么做

这是我获取请求者下数据的片段

package com.example.together.fragment;


public class PetchingLoungeFragment extends Fragment {

    private static final String TAG = "PetFirendsFragment";

    RecyclerView recyclerView;
    PetchingLoungeAdapter petchingLoungeAdapter;
    List<Lounge> requestorUserList;
    FirebaseUser firebaseUser;



    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {

        Log.d(TAG, "분양키 리스트 목록처음"+requestorUserList);

        View view =  inflater.inflate(R.layout.fragment_pet_firends, container, false);

        recyclerView = view.findViewById(R.id.recycler_view);
        recyclerView.setHasFixedSize(true);



        firebaseUser = FirebaseAuth.getInstance().getCurrentUser();

        DatabaseReference reference = FirebaseDatabase.getInstance().getReference("PetchingBunyang").child(firebaseUser.getUid()).child("Requestor");
        reference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot)
            {


                for (DataSnapshot childSnapshot : dataSnapshot.getChildren())
                {
                    Lounge lounge = childSnapshot.getValue(Lounge.class);
                    String key = childSnapshot.getKey();

                    Log.d(TAG, "라운지키"+key);

                    //각 신청키
                    lounge.setRequestorId(key);

                    requestorUserList.add(lounge);

                    Log.d(TAG, "신청자키: "+requestorUserList);
                    Log.d(TAG, "신청: "+lounge);


                }


                Collections.reverse(requestorUserList);
                petchingLoungeAdapter.notifyDataSetChanged();

            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });



        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getContext());
        recyclerView.setLayoutManager(linearLayoutManager);
        requestorUserList = new ArrayList<>();
        petchingLoungeAdapter = new PetchingLoungeAdapter(getContext(), requestorUserList);
        recyclerView.setAdapter(petchingLoungeAdapter);



        return view;


    }


}

package com.example.together.adapter;

public class PetchingLoungeAdapter extends RecyclerView.Adapter<PetchingLoungeAdapter.MyViewHolder> {


    private static final String TAG = "PetchingBunyangAdapter";

    FirebaseUser firebaseUser;
    DatabaseReference reference;

    Context mContext;
    List<Lounge> mLounge;

    public PetchingLoungeAdapter(Context mContext, List<Lounge> mLounge) {
        this.mContext = mContext;
        this.mLounge = mLounge;
    }



    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

        View view = LayoutInflater.from(mContext).inflate(R.layout.list_petching_lounge, parent, false);
        return new PetchingLoungeAdapter.MyViewHolder(view);

    }

    @Override
    public void onBindViewHolder(MyViewHolder viewHolder, int position)
    {

        final Lounge lounge = mLounge.get(position);
        getRequestorUserInfo(lounge.getRequestorId(), viewHolder.img_requestor, viewHolder.requestor_name);



        viewHolder.img_requestor.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View v)
            {
                Intent intent = new Intent(v.getContext(), PetchingBunyangDetailInfo.class);

               // intent.putExtra("petBunyangId",mUser.get(position).getPetBunyangId());

                mContext.startActivity(intent);


            }
        });

    }

    @Override
    public int getItemCount()
    {
        return mLounge.size();
                //mPetchingLounge.size();
    }



    public class MyViewHolder extends RecyclerView.ViewHolder
    {

        public Button allow, refuse;
        public ImageView img_requestor;
        public TextView requestor_name;

        public MyViewHolder(View itemView)
        {
            super(itemView);

            img_requestor = itemView.findViewById(R.id.img_requestor);

            allow = itemView.findViewById(R.id.allow);
            refuse = itemView.findViewById(R.id.refuse);

            requestor_name = itemView.findViewById(R.id.requestor_name);


        }
    }



    // 펫 정보 이름, 나이, 견종, 성별,
    private void getRequestorUserInfo(String petbunyangid, final ImageView imageView, final TextView petName)
    {


        firebaseUser = FirebaseAuth.getInstance().getCurrentUser();

        DatabaseReference reference = FirebaseDatabase.getInstance().getReference("Users").child(firebaseUser.getUid()).child("Requestor").child(petbunyangid);
        reference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                Lounge lounge = dataSnapshot.getValue(Lounge.class);

                lounge.getRequestorId();

            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });

    }



}

package com.example.together.fragment；
公共类PetchingLoungeFragment扩展了片段{
私有静态最终字符串TAG=“PetFirendsFragment”；
回收视图回收视图；
小矮人小矮人；
列表请求者用户列表；
FirebaseUser FirebaseUser；
@凌驾
CreateView上的公共视图（布局、充气机、视图组容器、捆绑包保存状态）
{
Log.d（标记，“분양키 리스트 목록처음"+请求者用户列表）；
视图=充气机。充气（R.layout.fragment\u pet\u firends，container，false）；
recyclerView=view.findViewById（R.id.recycler\u视图）；
recyclerView.setHasFixedSize（true）；
firebaseUser=FirebaseAuth.getInstance（）.getCurrentUser（）；
DatabaseReference=FirebaseDatabase.getInstance（）.getReference（“PetchingBunyang”）.child（firebaseUser.getUid（））.child（“请求者”）；
addValueEventListener（新的ValueEventListener（）{
@凌驾
public void onDataChange（@NonNull DataSnapshot DataSnapshot）
{
对于（DataSnapshot childSnapshot:DataSnapshot.getChildren（））
{
Lounge Lounge=childSnapshot.getValue（Lounge.class）；
String key=childSnapshot.getKey（）；
Log.d（标记，“라운지키“+键）；
//각 신청키
lounge.setRequestorId（钥匙）；
requestorUserList.add（休息室）；
Log.d（标记，“신청자키: “+请求者用户列表）；
Log.d（标记，“신청: “+休息室）；
}
集合。反向（请求者用户列表）；
petchingLoungeAdapter.notifyDataSetChanged（）；
}
@凌驾
已取消的公共void（@NonNull DatabaseError DatabaseError）{
}
});
LinearLayoutManager LinearLayoutManager=新的LinearLayoutManager（getContext（））；
recyclerView.setLayoutManager（linearLayoutManager）；
requestorUserList=新的ArrayList（）；
petchingLoungeAdapter=新的petchingLoungeAdapter（getContext（），requestorUserList）；
recyclerView.setAdapter（petchingLoungeAdapter）；
返回视图；
}
}

这是我的回收器视图适配器

package com.example.together.fragment;


public class PetchingLoungeFragment extends Fragment {

    private static final String TAG = "PetFirendsFragment";

    RecyclerView recyclerView;
    PetchingLoungeAdapter petchingLoungeAdapter;
    List<Lounge> requestorUserList;
    FirebaseUser firebaseUser;



    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {

        Log.d(TAG, "분양키 리스트 목록처음"+requestorUserList);

        View view =  inflater.inflate(R.layout.fragment_pet_firends, container, false);

        recyclerView = view.findViewById(R.id.recycler_view);
        recyclerView.setHasFixedSize(true);



        firebaseUser = FirebaseAuth.getInstance().getCurrentUser();

        DatabaseReference reference = FirebaseDatabase.getInstance().getReference("PetchingBunyang").child(firebaseUser.getUid()).child("Requestor");
        reference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot)
            {


                for (DataSnapshot childSnapshot : dataSnapshot.getChildren())
                {
                    Lounge lounge = childSnapshot.getValue(Lounge.class);
                    String key = childSnapshot.getKey();

                    Log.d(TAG, "라운지키"+key);

                    //각 신청키
                    lounge.setRequestorId(key);

                    requestorUserList.add(lounge);

                    Log.d(TAG, "신청자키: "+requestorUserList);
                    Log.d(TAG, "신청: "+lounge);


                }


                Collections.reverse(requestorUserList);
                petchingLoungeAdapter.notifyDataSetChanged();

            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });



        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getContext());
        recyclerView.setLayoutManager(linearLayoutManager);
        requestorUserList = new ArrayList<>();
        petchingLoungeAdapter = new PetchingLoungeAdapter(getContext(), requestorUserList);
        recyclerView.setAdapter(petchingLoungeAdapter);



        return view;


    }


}

package com.example.together.adapter;

public class PetchingLoungeAdapter extends RecyclerView.Adapter<PetchingLoungeAdapter.MyViewHolder> {


    private static final String TAG = "PetchingBunyangAdapter";

    FirebaseUser firebaseUser;
    DatabaseReference reference;

    Context mContext;
    List<Lounge> mLounge;

    public PetchingLoungeAdapter(Context mContext, List<Lounge> mLounge) {
        this.mContext = mContext;
        this.mLounge = mLounge;
    }



    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

        View view = LayoutInflater.from(mContext).inflate(R.layout.list_petching_lounge, parent, false);
        return new PetchingLoungeAdapter.MyViewHolder(view);

    }

    @Override
    public void onBindViewHolder(MyViewHolder viewHolder, int position)
    {

        final Lounge lounge = mLounge.get(position);
        getRequestorUserInfo(lounge.getRequestorId(), viewHolder.img_requestor, viewHolder.requestor_name);



        viewHolder.img_requestor.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View v)
            {
                Intent intent = new Intent(v.getContext(), PetchingBunyangDetailInfo.class);

               // intent.putExtra("petBunyangId",mUser.get(position).getPetBunyangId());

                mContext.startActivity(intent);


            }
        });

    }

    @Override
    public int getItemCount()
    {
        return mLounge.size();
                //mPetchingLounge.size();
    }



    public class MyViewHolder extends RecyclerView.ViewHolder
    {

        public Button allow, refuse;
        public ImageView img_requestor;
        public TextView requestor_name;

        public MyViewHolder(View itemView)
        {
            super(itemView);

            img_requestor = itemView.findViewById(R.id.img_requestor);

            allow = itemView.findViewById(R.id.allow);
            refuse = itemView.findViewById(R.id.refuse);

            requestor_name = itemView.findViewById(R.id.requestor_name);


        }
    }



    // 펫 정보 이름, 나이, 견종, 성별,
    private void getRequestorUserInfo(String petbunyangid, final ImageView imageView, final TextView petName)
    {


        firebaseUser = FirebaseAuth.getInstance().getCurrentUser();

        DatabaseReference reference = FirebaseDatabase.getInstance().getReference("Users").child(firebaseUser.getUid()).child("Requestor").child(petbunyangid);
        reference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                Lounge lounge = dataSnapshot.getValue(Lounge.class);

                lounge.getRequestorId();

            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });

    }



}

package com.example.together.adapter；
公共类PetchingLoungLeadapter扩展了RecyclerView.Adapter{
私有静态最终字符串标记=“PetchingBunyangAdapter”；
FirebaseUser FirebaseUser；
数据库参考；
语境；
名单公告；
公共PetchingLoungHeadapter（上下文mContext，列表消息）{
this.mContext=mContext；
this.mLounge=mLounge；
}
@非空
@凌驾
public MyViewHolder onCreateViewHolder（@NonNull ViewGroup父级，int-viewType）{
视图=布局更平坦。从（mContext）。充气（R.layout.list\u petching\u lounge，parent，false）；
返回新的PetchingLoungeAdapter.MyViewHolder（视图）；
}
@凌驾
BindViewHolder上的公共无效（MyViewHolder viewHolder，int位置）
{
最终休息室=m休息室获得（位置）；
getRequestorUserInfo（lounge.getRequestorId（），viewHolder.img_requestor，viewHolder.requestor_name）；
viewHolder.img_requestor.setOnClickListener（新视图.OnClickListener（）
{
@凌驾
公共void onClick（视图v）
{
Intent Intent=newintent（v.getContext（），PetchingBunyangDetailInfo.class）；
//intent.putExtra（“petBunyangId”，mUser.get（position.getPetBunyangId（））；
mContext.startActivity（意图）；
}
});
}
@凌驾
public int getItemCount（）
{
返回mLounge.size（）；
//mPetchingLounge.size（）；
}
公共类MyViewHolder扩展了RecyclerView.ViewHolder
{
公共按钮允许、拒绝；
公共图像视图img_请求者；
公共文本视图请求者名称；
公共MyViewHolder（查看项目视图）
{
超级（项目视图）；
img_requestor=itemView.findviewbyd（R.id.img_requestor）；
allow=itemView.findviewbyd（R.id.allow）；
拒绝=itemView.findViewById（R.id.Reject）；
requestor_name=itemView.findviewbyd（R.id.requestor_name）；
}
}
// 펫 정보 이름, 나이, 견종, 성별,
私有void getRequestorUserInfo（字符串petbunyangid、最终图像视图ImageView、最终文本视图petName）
{
firebaseUser=FirebaseAuth.getInstance（）.getCurrentUser（）；
DatabaseReference=FirebaseDatabase.getInstance（）.getReference（“用户”）.child（firebaseUser.getUid（））.child（“请求者”）.child（petbunyangid）；
addValueEventListener（新的ValueEventListener（）{
@凌驾
public void onDataChange（@NonNull DataSnapshot DataSnapshot）{
Lounge Lounge=dataSnapshot.getValue（Lounge.class）；
lounge.getRequestorId（）；
}
@凌驾
已取消的公共void（@NonNull DatabaseError DatabaseError）{
}
});
}
}

尝试以下操作：

DatabaseReference reference = FirebaseDatabase.getInstance().getReference("PetchingBunyang").child(firebaseUser.getUid()).child("Requestor");
DatabaseReference userReference = FirebaseDatabase.getInstance().getReference("Users");

reference.addValueEventListener(new ValueEventListener() {
 @Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot datas: dataSnapshot.getChildren()){
     for(DataSnapshot ds : datas.getChildren()){
          String id = ds.getKey();

          userReference.child(id).addValueEventListener(new ValueEventListener() {
              @Override
           public void onDataChange(DataSnapshot dataSnapshot) {
                String fullName = dataSnapshot.child("fullname").getValue(String.class);
                String imageUrl = dataSnapshot.child("imageUrl").getValue(String.class);
               }
              @Override
          public void onCancelled(@NonNull DatabaseError databaseError) { 
             throw databaseError.toException(); 
               }
           });
      }
    }
 }
   @Override
public void onCancelled(@NonNull DatabaseError databaseError) { 
     throw databaseError.toException(); 
    }
 });

首先添加对子

请求者的引用

，然后在其中循环两次，以便能够获取值为

true

的

用户ID

。然后在检索

用户ID

后，添加另一个引用