使用 FirebaseRecyclerAdapter 的 RecyclerView 不显示项目 - FirebaseUI (3.1.3) [重复]

Question

我一直在处理我的应用程序，我想要一个 fragment 来显示建议的用户要关注（显示来自数据库 child("users") 的一些用户，但是当我设置我的RecyclerView 时，没有显示任何项目（配置文件） 所以这是我的片段布局：

RecyclerView 就在建议用户下方.. 它没有显示任何数据， 这是我的 XML 项目：

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <de.hdodenhof.circleimageview.CircleImageView
            android:layout_width="@dimen/_60sdp"
            android:src="@drawable/profile"
            android:id="@+id/user_in_list_image"
            app:border_color="#fff"
            android:layout_margin="@dimen/_10sdp"
            app:border_width="3dp"
            android:layout_height="@dimen/_60sdp" />
        <LinearLayout
            android:orientation="vertical"
            android:layout_gravity="center"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content">
            <TextView
                android:text="User203"
                android:textStyle="bold"
                android:id="@+id/user_in_list_username"
                android:textSize="@dimen/_14sdp"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content" />
            <TextView
                android:text="El Eulma, Algeria"
                android:textSize="@dimen/_12sdp"
                android:id="@+id/user_in_list_info"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content" />
            <com.like.LikeButton
                android:id="@+id/user_in_list_followButton"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignParentEnd="true"
                android:layout_alignParentRight="true"
                android:layout_alignParentTop="true"
                app:icon_size="@dimen/_16sdp"
                app:is_enabled="true"
                app:icon_type="thumb" />
        </LinearLayout>
        <RelativeLayout
            android:layout_gravity="center"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">
            <com.like.LikeButton
                android:layout_marginRight="@dimen/_30sdp"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignParentEnd="true"
                android:layout_alignParentRight="true"
                android:layout_alignParentTop="true"
                app:icon_size="@dimen/_16sdp"
                android:layout_gravity="center|end"
                app:is_enabled="true"
                app:icon_type="heart" />
        </RelativeLayout>

    </LinearLayout>

</FrameLayout>

这是我的Object Modeljava.class：

public class User {
public String name;
public String gender;
public String birthday;
public String work;
public String country;
public String language;
public String city;
public String postal;

public User() {
    // Default constructor required for calls to DataSnapshot.getValue(User.class)
}

public User(String name ,String gender, String birthday, String work , String country,String language , String city ,String postal) {
    this.name = name;
    this.gender = gender;
    this.birthday = birthday;
    this.work = work;
    this.country = country;
    this.language = language;
    this.city = city;
    this.postal = postal;
}

public String getName() { return name; }

public String getGender() { return gender; }

public String getBirthday() { return birthday; }

public String getWork() { return work; }

public String getCountry() { return country; }

public String getLanguage() { return language; }

public String getCity() { return city; }

public String getPostal() { return postal; }

}

这是我的ViewHolderjava.class：

public class users_holder extends RecyclerView.ViewHolder{
private static final String TAG = users_holder.class.getSimpleName();
public TextView userName,userInfo;
public CircleImageView userImage;
public com.like.LikeButton likeButton;
public users_holder(View itemView) {
    super(itemView);
    userName= itemView.findViewById(R.id.user_in_list_username);
    userInfo = itemView.findViewById(R.id.user_in_list_info);
    userImage = itemView.findViewById(R.id.user_in_list_image);
    likeButton = itemView.findViewById(R.id.user_in_list_followButton);
}
}

这是我的 framgent.java onCreateView：

 public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View view = inflater.inflate(R.layout.fragment_discover, container, false);
    if (mListener != null) {
        mListener.onFragmentInteraction("Discover");

    }

    mUser = FirebaseAuth.getInstance().getCurrentUser();
    mUid = mUser.getUid();
    mDatabase = FirebaseDatabase.getInstance();
    mDatabaseref = mDatabase.getReference().child("users");
    suggestedRecycler = view.findViewById(R.id.Suggested_users_recycler);
    mLayoutManager = new LinearLayoutManager(getContext());
    suggestedRecycler.setLayoutManager(mLayoutManager);
    FirebaseRecyclerOptions<User> options = new FirebaseRecyclerOptions.Builder<User>()
            .setQuery(mDatabaseref, User.class).build();

    FirebaseRecyclerAdapter<User, users_holder> adapter = new FirebaseRecyclerAdapter<User, users_holder>(options) {
        @Override
        protected void onBindViewHolder(@NonNull users_holder holder, int position, @NonNull User model) {
                holder.userName.setText(model.getName());
                holder.userInfo.setText(model.getCity() + ", " + model.getCountry());
        }

        @Override
        public users_holder onCreateViewHolder(ViewGroup parent, int viewType) {
            // Create a new instance of the ViewHolder, in this case we are using a custom
            // layout called R.layout.message for each item
            View view = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.user_in_list, parent, false);

            return new users_holder(view);
        }

    };
    suggestedRecycler.setAdapter(adapter);




    return view;
}

我在做什么错？当你不得不在外部class中设置adapter时，我看到其他版本都很好，谢谢！

Answer 1

Peter Hadad 的 回答在这里对我有用： Android ListView adapter not pushing individual items for chat app - Firebase-Ui 3.1 ，所以你需要使用这个：

@Override
protected void onStart() {
super.onStart();
adapter.startListening();
}


@Override
protected void onStop() {
super.onStop();
adapter.stopListening();
}

由于FirebaseListAdapter 使用侦听器来检查firebase 数据库中的更改，因此要侦听数据，您需要在onStart() 中添加adapter.startListening() 以便能够在列表视图中显示数据。 然后在onStop() 内部，你可以使用adapter.stopListening() 将监听器和数据从适配器中移除。