如何使用Firebase Firestore进行用户名搜索？

Question

I am currently trying to implement a search method via a Firestore query so the user can search other users by typing in their username in an EditText which should display the result in a RecyclerView. I tried some other variants of code but it seems that the query is never triggered and I don't know where the problem is. Any help is much appreciated!

Here is my activity with the search field:

public class PlayerSearch extends AppCompatActivity {

    private EditText searchField;
    private View okBtn;

    private FirebaseFirestore db = FirebaseFirestore.getInstance();
    private CollectionReference userRef = db.collection("User");

    private UserAdapter userAdapter;

    // TODO: 2019-11-11 Make a method that takes the input of the EditText and make a query in Firestore to search a player and display the result

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

        searchField = findViewById(R.id.edit_text_search);
        okBtn = findViewById(R.id.search_player_ok);

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

        String searchText = searchField.getText().toString();

        okBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                search(searchText);

            }
        });
    }

    private void search(String searchText) {
        Query query = userRef.orderBy("username").startAt(searchText).endAt(searchText + "\uf8ff");

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

        userAdapter = new UserAdapter(options);

    }

Here is my UserAdapter:

public class UserAdapter extends FirestoreRecyclerAdapter<Users, UserAdapter.UserHolder> {

    public UserAdapter(@NonNull FirestoreRecyclerOptions<Users> options) {
        super(options);
    }

    @Override
    protected void onBindViewHolder(@NonNull UserHolder holder, int position, @NonNull Users model) {

        holder.textViewUsername.setText(model.getUsername());

    }

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

    class UserHolder extends RecyclerView.ViewHolder {

        TextView textViewUsername;

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

            textViewUsername = itemView.findViewById(R.id.player_name_search);
        }
    }
}

And here is my User class:

public class Users {

    public Users (){

    }

    public String username;

    public String getUsername() {
        return username;
    }

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

    public Users(String username) {
        this.username = username;
    }
    }

Answer 1

Your search method creates a new adapter, but doesn't associate it with the recyclerView in any way.

So you'll need something like:

private void search(String searchText) {
    Query query = userRef.orderBy("username").startAt(searchText).endAt(searchText + "\uf8ff");

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

    userAdapter = new UserAdapter(options);

    RecyclerView recyclerView = findViewById(R.id.recycler_view_search_player)

    recyclerView.setAdapter(userAdapter);
}