基本上，我想要做的是使用FirebaseRecyclerAdapter并用我定制设计的RecyclerView填充CardView。更新版本的代码已更改，因此，我尝试实现它但不起作用。这是我一年前写的代码，工作正常，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，但问题是这个代码没有填充我的recyclerView（我需要做什么改变才能用我的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课程：
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);
}
}
这是我的模型类的getter和setter：
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 + '\'' +
'}';
}
}
现在我需要做些什么改变？
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);
}
}
}
为了能够显示Firebase实时数据库中的数据，您需要开始侦听更改，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，如下所示：
@Override
protected void onStop() {
super.onStop();
if(FBRA != null) {
FBRA.stopListening();
}
}
请参阅我在post的回答，我已经解释了为什么要删除听众。
附：另外，请不要忘记将FBRA作为全局变量，并从对象的声明中删除FirebaseRecyclerAdapter<ServiceClass, ServiceViewHolder>。
这更像是一个建议。如果你想继续使用旧方法填充你的recyclerview，即“populateViewHolder”方法而不是新的“onBindViewHolder”方法，只需使用它;
implementation 'com.firebaseui:firebase-ui:1.0.1'
而不是升级firebase-ui版本