java FirebaseRecyclerAdapter未在我的RecyclerView布局中显示数据

Question

请注意，有很多这样的问题，但没有一个适合我。 我一直试图在回收器视图中显示数据，但它没有显示数据，也没有抛出任何错误 这是我的密码

我已经包括了最新版本的Firebase依赖项和最新版本的Firebase UI数据库

依赖项版本

// Firebase
implementation 'com.google.firebase:firebase-auth:19.2.0'
implementation 'com.google.firebase:firebase-database:19.2.1'
implementation 'com.google.firebase:firebase-storage:19.1.1'

// Firebase UI
implementation 'com.firebaseui:firebase-ui-database:6.0.2'

这是电影课 电影。java

package com.dipeshpatil.in;

public class Films {

    public String name, year;

    public Films(String name, String year) {
        this.name = name;
        this.year = year;
    }

    public Films() {

    }

    public String getName() {
        return name;
    }

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

    public String getYear() {
        return year;
    }

    public void setYear(String year) {
        this.year = year;
    }
}

这是ViewHolder类FilmsViewHolder。java

package com.dipeshpatil.in;

import 安卓.view.View;
import 安卓.widget.TextView;

import 安卓x.recyclerview.widget.RecyclerView;

public class FilmsViewHolder extends RecyclerView.ViewHolder {
    public TextView mFilmName;
    public TextView mFilmYear;

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

        mFilmName = itemView.findViewById(R.id.user_single_name);
        mFilmYear = itemView.findViewById(R.id.user_single_status);
    }
}

这是我应该在回收器视图FilmsActivity中显示数据的活动。java

public class FilmsActivity extends AppCompatActivity {

    private RecyclerView mFilmsList;
    private DatabaseReference mFilmsDatabase;
    private FirebaseRecyclerOptions<Films> options;
    private FirebaseRecyclerAdapter<Films, FilmsViewHolder> adapter;

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

        mFilmsList = findViewById(R.id.films_list);
        mFilmsList.setHasFixedSize(true);

        mFilmsDatabase = FirebaseDatabase.getInstance().getReference().child("Films");

        options = new FirebaseRecyclerOptions.Builder<Films>()
                .setQuery(mFilmsDatabase, Films.class)
                .build();

        adapter = new FirebaseRecyclerAdapter<Films, FilmsViewHolder>(options) {
            @Override
            protected void onBindViewHolder(FilmsViewHolder filmsViewHolder, int i, Films films) {

                filmsViewHolder.mFilmName.setText(films.getName());
                filmsViewHolder.mFilmYear.setText(films.getYear());
            }

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

                View mView = LayoutInflater.from(parent.getContext())
                        .inflate(R.layout.users_single_layout, parent, false);

                return new FilmsViewHolder(mView);
            }
        };
        mFilmsList.setAdapter(adapter);
    }

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

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

现在老实说，我没有得到任何类型的错误，这将有助于我调试代码和检查问题，同时它也没有显示我想要的输出

电影Firebase数据库

"Films" : {
    "01" : {
      "name" : "The Prestige",
      "year" : 2002
    },
    "02" : {
      "name" : "Fight Club",
      "year" : 1999
    }
}

布局文件活动\u胶片。xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:安卓="http://schemas.安卓.com/apk/res/安卓"
    xmlns:app="http://schemas.安卓.com/apk/res-auto"
    xmlns:tools="http://schemas.安卓.com/tools"
    安卓:layout_width="match_parent"
    安卓:layout_height="wrap_content"
    安卓:orientation="vertical"
    tools:context=".FilmsActivity">

    <安卓x.recyclerview.widget.RecyclerView
        安卓:layout_width="match_parent"
        安卓:layout_height="match_parent"
        安卓:padding="16dp"
        安卓:id="@+id/films_list" />
</LinearLayout>

Answer 1

com.google.firebase.database.DatabaseException: Failed to convert value of type java.lang.Long to String

首先，当您试图在模型中将Long转换为String时，它应该是InvocationTargetException[根据您的数据库结构。尝试更新您的模型，如下所示：

public class Films {
    public String name;
    public int year;

    ....
}

那么，你应该将LayoutManager设置为RecyclerView

LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
mFilmsList.setLayoutManager(linearLayoutManager);

更新：您必须更新onBindViewHolder以将int转换为字符串，然后使用String.valueOf将其设置为文本视图

@Override
protected void onBindViewHolder(FilmsViewHolder filmsViewHolder, int i, Films films) {

    filmsViewHolder.mFilmName.setText(films.getName());
    filmsViewHolder.mFilmYear.setText(String.valueOf(films.getYear()));
}

Answer 2

我认为Firebase查询的回复通常会延迟。可能就是这样。初始化适配器时，“选项”列表仍然为空

您很可能需要使用线程同步来实现这一点