Android - RecyclerView not working

问题

I am trying to retrieve data from my Firebase database, but my screen is not showing anything. I don't see any errors so I don't know why nothing is happening. Can anyone spot any mistakes? I followed the FirebaseUI guide with some help from a stackoverflow member. The data should show the street and the user on the screen

Fragment:

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

    View rootView = inflater.inflate(R.layout.fragment_stopandmap, container, false);

    Query keyQuery = FirebaseDatabase.getInstance().getReference("/Addresses/Street 10/users");
    DatabaseReference dataRef = FirebaseDatabase.getInstance().getReference("/User");
    recyclerView = (RecyclerView) rootView.findViewById(R.id.recyclerview);
    recyclerView.setHasFixedSize(true);
    recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));

    FirebaseRecyclerOptions<User> options = new FirebaseRecyclerOptions.Builder<User>()
            .setIndexedQuery(keyQuery, dataRef, User.class)
            .build();

    FirebaseRecyclerAdapter adapter = new FirebaseRecyclerAdapter<User, BetViewHolder>(options) {
        @Override
        public BetViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            View view = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.item_row, parent, false);

            return new BetViewHolder(view);
        }

        @Override
        protected void onBindViewHolder(BetViewHolder holder, int position, User model) {
            holder.setUserName(model.getUsername());
        }


    };

    recyclerView.setAdapter(adapter);

    return rootView;


}


public static class BetViewHolder extends RecyclerView.ViewHolder {

    TextView tw;

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

        tw = (TextView) itemView.findViewById(R.id.usersTextview);
    }

    public void setUserName(String username) {
        tw.setText("Hej" + username);
        Log.e("Activity", "In Vehicle " + username);

    }
}

User class:

public class User {
    private String username;
    private String usertype;

    public User() {
    }

    public String getUsername() {
        return this.username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getUsertype() {
        return usertype;
    }

    public void setUsertype(String usertype) {
        this.usertype = usertype;
    }
}

回答1:

In version 3.0 of FirebaseUI, you need to explicitly call startListening() & stopListening() on the adapter to instruct it to start/stop retrieving data from the database.

Adapter Lifecycle - in previous versions the adapters began listening immediately upon instantiation and had a cleanup() call to stop listening. In 3.x you must explicitly call startListening() and stopListening() or pass a LifecycleOwner to the options builder.

Source: Upgrading to FirebaseUI 3.0

来源：https://stackoverflow.com/questions/46744498/android-recyclerview-not-working