如何在 Android 3.1 及更高版本的较新版本中实施 Firebase Recycler Adapter？

Question

基本上，我想做的是使用 FirebaseRecyclerAdapter 并用我自定义设计的 CardView 填充 RecyclerView。新版本的代码已经更改，因此，我尝试实现它但没有成功。这是我一年前写的代码，运行良好并填充了我的 RecyclerView:

FirebaseRecyclerAdapter<DataClass,DataViewHolder> FBRA= new FirebaseRecyclerAdapter<DataClass, DataViewHolder>(
            DataClass,
            R.layout.myCardView,
            DataViewHolder.class,
            databaseReference
    ) {
        @Override
        protected void populateViewHolder(DataViewHolder viewHolder, DataClass model, int position) {
            viewHolder.setTitle(model.gettitle());
            viewHolder.setDate(model.getDate());
        }
   }; 
  myRecyclerView.setAdapter(FBRA);

现在我们必须使用这样的东西，但问题是此代码未填充我的 recyclerView（我需要在此处进行哪些更改才能使用我的 cardView 填充我的 recyclerView？）

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

    Query query = FirebaseDatabase.getInstance()
            .getReference()
            .child("Official_Services");

    FirebaseRecyclerOptions<ServiceClass> options = new FirebaseRecyclerOptions.Builder<ServiceClass>()
            .setQuery(query, ServiceClass.class)
            .build();

    FirebaseRecyclerAdapter<ServiceClass, ServiceViewHolder> FBRA = new FirebaseRecyclerAdapter<ServiceClass, ServiceViewHolder>(options) {

        @NonNull
        @Override
        public ServiceViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int i) {

            View view = LayoutInflater.from(HomeActivity.this).inflate(R.layout.service_card, parent, false);

            return new ServiceViewHolder(view);

        }

        @Override
        protected void onBindViewHolder(@NonNull ServiceViewHolder holder, int position, @NonNull ServiceClass model) {

            holder.setServiceName(model.getServiceName());

            holder.setServiceCaption(model.getServiceCaption());

        }

    };

    mServiceList.setAdapter(FBRA);

}

这是我的 ViewHolder class:

public static class ServiceViewHolder extends RecyclerView.ViewHolder {

    public ServiceViewHolder(View itemView) {

        super(itemView);

        View mView = itemView;

    }

    public void setServiceName(String serviceName) {

        TextView sName = itemView.findViewById(R.id.serviceName);

        sName.setText(serviceName);

    }

    public void setServiceCaption(String serviceCaption) {

        TextView sCaption = itemView.findViewById(R.id.serviceCap);

        sCaption.setText(serviceCaption);
    }

}

这是我的 getter 和 setter 模型 class：

public class ServiceClass {

private String serviceName;
private String serviceCode;
private String serviceCaption;
private String serviceIconUrl;

public ServiceClass() {
}

public ServiceClass(String serviceName, String serviceCode, String serviceCaption, String serviceIconUrl) {
    this.serviceName = serviceName;
    this.serviceCode = serviceCode;
    this.serviceCaption = serviceCaption;
    this.serviceIconUrl = serviceIconUrl;
}

public String getServiceName() {
    return serviceName;
}

public String getServiceCode() {
    return serviceCode;
}

public String getServiceCaption() {
    return serviceCaption;
}

public String getServiceIconUrl() {
    return serviceIconUrl;
}

public void setServiceName(String serviceName) {
    this.serviceName = serviceName;
}

public void setServiceCode(String serviceCode) {
    this.serviceCode = serviceCode;
}

public void setServiceCaption(String serviceCaption) {
    this.serviceCaption = serviceCaption;
}

public void setServiceIconUrl(String serviceIconUrl) {
    this.serviceIconUrl = serviceIconUrl;
}

@Override
public String toString() {
    return "ServiceClass{" +
            "serviceName='" + serviceName + '\'' +
            ", serviceCode='" + serviceCode + '\'' +
            ", serviceCaption='" + serviceCaption + '\'' +
            ", serviceIconUrl='" + serviceIconUrl + '\'' +
            '}';
}
}

现在我需要做哪些改变？

这是我的整个 java 文件：

public class HomeActivity extends AppCompatActivity {

    private RecyclerView mServiceList;

    private FirebaseDatabase mDatabase;

    private DatabaseReference myRef;

    FirebaseRecyclerAdapter<ServiceClass, ServiceViewHolder> FBRA;

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

        BottomNavigationViewEx bottomNavigationViewEx = findViewById(R.id.navViewBar);

        bottomNavigationViewEx.enableAnimation(false);

        bottomNavigationViewEx.enableShiftingMode(false);

        bottomNavigationViewEx.setTextVisibility(false);

        Calligrapher calligrapher = new Calligrapher(this);

        calligrapher.setFont(this, "Helvetica.ttf", true);

        mServiceList = findViewById(R.id.serviceRV);

        mServiceList.setHasFixedSize(true);

        mServiceList.setLayoutManager(new LinearLayoutManager(this));

        mDatabase = FirebaseDatabase.getInstance();

        myRef = mDatabase.getReference().child("Official_Services");

    }

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

        FBRA.startListening();

        Query query = myRef;

        FirebaseRecyclerOptions<ServiceClass> options = new FirebaseRecyclerOptions.Builder<ServiceClass>()
                .setQuery(query, ServiceClass.class)
                .build();

        FBRA = new FirebaseRecyclerAdapter<ServiceClass, ServiceViewHolder>(options) {

            @NonNull
            @Override
            public ServiceViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int i) {

                View view = LayoutInflater.from(HomeActivity.this).inflate(R.layout.service_card, parent, false);

                return new ServiceViewHolder(view);

            }

            @Override
            protected void onBindViewHolder(@NonNull ServiceViewHolder holder, int position, @NonNull ServiceClass model) {

                holder.setServiceName(model.getServiceName());

                holder.setServiceCaption(model.getServiceCaption());

            }

        };

        mServiceList.setAdapter(FBRA);



    }



    public static class ServiceViewHolder extends RecyclerView.ViewHolder {

        public ServiceViewHolder(View itemView) {

            super(itemView);

            View mView = itemView;

        }

        public void setServiceName(String serviceName) {

            TextView sName = itemView.findViewById(R.id.serviceName);

            sName.setText(serviceName);

        }

        public void setServiceCaption(String serviceCaption) {

            TextView sCaption = itemView.findViewById(R.id.serviceCap);

            sCaption.setText(serviceCaption);
        }

    }

}

Answer 1

为了能够显示来自 Firebase 实时数据库的数据，您需要开始监听更改，为此您应该在 onStart() 方法中添加以下代码行：

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

要停止侦听更改，您需要在 onStop() 方法中添加以下代码行：

@Override
protected void onStop() {
    super.onStop();
    if(FBRA != null) {
        FBRA.stopListening();
    }
}

请参阅我在中的回答，我在其中解释了为什么您应该删除侦听器。

P.S。也请不要忘记将 FBRA 设为全局变量并从对象声明中删除 FirebaseRecyclerAdapter<ServiceClass, ServiceViewHolder>。

Answer 2

这更像是一个建议。如果您想继续使用旧方法来填充您的 recyclerview 即 "populateViewHolder" 方法而不是新的 "onBindViewHolder" 方法只使用这个;

implementation 'com.firebaseui:firebase-ui:1.0.1'

而不是升级的 firebase-ui 版本

如何在 Android 3.1 及更高版本的较新版本中实施 Firebase Recycler Adapter？

How to implement Firebase Recycler Adapter in newer version of Android 3.1 and higher?

java

android

firebase

firebase-realtime-database

firebaseui