无法从 Android Firebase 数据库接收字符串

Question

我想从我的 firebase 数据库中获取名称（字符串）和位置（字符串）到我的应用程序片段页面的列表视图中。它没有给出任何错误，但名称和位置文本只是不出现在应用程序上。感谢帮助。我认为从 firebase 服务器获取字符串存在问题。

Firebase hierarchy : FIREBASE -> Events -> XmasParty -> location = Germany
                                                     -> name = XmasParty

片段：

public class RequestsFragment extends Fragment {


    private Button create_event_btn;
    private View mMainView2;
    private RecyclerView mEventList;
    private DatabaseReference mEventsDatabase;
    private LinearLayoutManager mLayoutManager;


    public void ChatsFragment() {
        // Required empty public constructor
    }


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

        mMainView2 = inflater.inflate(R.layout.fragment_requests, container, false);
        mEventsDatabase = FirebaseDatabase.getInstance().getReference().child("Events");

        mLayoutManager = new LinearLayoutManager(getContext());
        create_event_btn = (Button) mMainView2.findViewById(R.id.create_btn);
        mEventList = (RecyclerView) mMainView2.findViewById(R.id.event_list);
        mEventList.setHasFixedSize(true);
        mEventList.setLayoutManager(mLayoutManager);



        create_event_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(getActivity(), Create_EventActivity.class);
                startActivity(intent);
            }
        });


        // Inflate the layout for this fragment
        return mMainView2;
    }

    @Override
    public void onStart() {
        super.onStart();

        FirebaseRecyclerAdapter<Events, RequestsFragment.EventsViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<Events, EventsViewHolder>(

                Events.class,
                R.layout.users_single_layout,
                RequestsFragment.EventsViewHolder.class,
                mEventsDatabase

        ) {
            @Override
            protected void populateViewHolder(RequestsFragment.EventsViewHolder eventsViewHolder, Events events, int position) {

                eventsViewHolder.setDisplayName(events.getName());
                eventsViewHolder.setUserStatus(events.getLocation());
               // usersViewHolder.setUserImage(users.getThumb_image(), getApplicationContext());

                final String event_id = getRef(position).getKey();

                eventsViewHolder.mView2.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View view) {

                        //Intent profileIntent = new Intent(UsersActivity.this, ProfileActivity.class);
                       // profileIntent.putExtra("user_id", user_id);
                       // startActivity(profileIntent);

                    }
                });

            }
        };


        mEventList.setAdapter(firebaseRecyclerAdapter);

    }


    public static class EventsViewHolder extends RecyclerView.ViewHolder {

        View mView2;

        public EventsViewHolder(View itemView2) {
            super(itemView2);

            mView2 = itemView2;

        }

        public void setDisplayName(String name){

            TextView userNameView = (TextView) mView2.findViewById(R.id.user_single_name);
            userNameView.setText(name);

        }

        public void setUserStatus(String status){

            TextView userStatusView = (TextView) mView2.findViewById(R.id.user_single_status);
            userStatusView.setText(status);


        }    

        }
    }
}

事件类

public class Events {

    public String name;
    public String location;
    public String time;



    public Events(){

    }

    public Events(String name, String location, String time) {
        this.name = name;
        this.location = location;
        this.time = time;
    }

    public String getName() {return name;}
    public void setName(String name) {
        this.name = name;
    }

    public String getLocation() {
        return location;
    }
    public void setLocation(String location) {
        this.location = location;
    }

    public String getTime() {return time;}
    public void setTime(String time) {this.time = time;}

}

Answer 1

要获取location和name的值，请使用以下代码：

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference yourRef = rootRef.child("Events").child("XmasParty");
ValueEventListener eventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        String location = dataSnapshot.child("location").getValue(String.class);
        String name = dataSnapshot.child("name").getValue(String.class);
        Log.d("TAG", location + " / " + name);
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {}
};
yourRef.addListenerForSingleValueEvent(eventListener);

输出将是：

Germany / XmasParty