【发布时间】：2021-05-28 03:11:27
【问题描述】：
我正在尝试使用 FireBase 数据库在片段上显示 RecyclerView，但由于某种未知原因，它给了我这个错误：E/RecyclerView: No adapter attach;我很确定我实际上连接了适配器，这是代码：
主要活动
public class MainActivity extends AppCompatActivity {
Fragment currentFragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if(savedInstanceState == null){
currentFragment = new MapsFragment();
changeFragment(currentFragment);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.menu,menu);
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(@NonNull MenuItem item) {
switch (item.getItemId()){
case R.id.menu_bookmarkList:
currentFragment = new ListaFragment();
break;
case R.id.menu_mapa:
currentFragment = new MapsFragment();
break;
}
changeFragment(currentFragment);
return super.onOptionsItemSelected(item);
}
private void changeFragment(Fragment currentFragment) {
getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,currentFragment).commit();
}
}
ListaFragment（应该显示 Recycler 的那个）：
public class ListaFragment extends Fragment implements MyAdapter.RecyclerItemClick{
private MyAdapter myAdapter;
private RecyclerView recycler;
FirebaseDatabase database;
DatabaseReference myRef;
public ListaFragment() {
// Required empty public constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState); }
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_lista, container, false);
database = FirebaseDatabase.getInstance();
myRef = database.getReference("Marcador");
recycler = (RecyclerView) v.findViewById(R.id.recyler);
recycler.setLayoutManager(new LinearLayoutManager(getContext()));
FirebaseRecyclerOptions<Marcador> options = new FirebaseRecyclerOptions.Builder<Marcador>()
.setQuery(myRef, Marcador.class).build();
myAdapter = new MyAdapter(options,this);
recycler.setAdapter(myAdapter);
return v;
}
@Override
public void onStart(){
super.onStart();
myAdapter.startListening();
}
@Override
public void onStop() {
super.onStop();
myAdapter.stopListening();
}
@Override
public void itemClick(Marcador marcador) {
}
}
我已经完成了适配器（我跳过了 xml，因为它们非常简单）：
public class MyAdapter extends FirebaseRecyclerAdapter<Marcador,MyAdapter.MarcadorHolder> {
private Context context;
private RecyclerItemClick itemClick;
public MyAdapter(@NonNull FirebaseRecyclerOptions<Marcador> options, RecyclerItemClick itemClick) {
super(options);
this.itemClick = itemClick;
}
@Override
protected void onBindViewHolder(@NonNull final MarcadorHolder holder, int position, @NonNull Marcador model) {
final Marcador marcador = getItem(position);
holder.textViewNom.setText(model.getNom());
holder.textViewLatitude.setText(String.valueOf(model.getLatitude()));
holder.textViewLongitude.setText(model.getLongitude());
holder.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
itemClick.itemClick(marcador);
}
});
}
@NonNull
@Override
public MarcadorHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.recylcer_view_item,parent,false);
context = parent.getContext();
return new MarcadorHolder(v);
}
public class MarcadorHolder extends RecyclerView.ViewHolder{
TextView textViewNom;
TextView textViewLatitude;
TextView textViewLongitude;
public MarcadorHolder(@NonNull View itemView) {
super(itemView);
textViewNom = itemView.findViewById(R.id.textViewNom);
textViewLatitude = itemView.findViewById(R.id.textViewLatitud);
textViewLongitude = itemView.findViewById(R.id.textViewLongitut);
}
}
public interface RecyclerItemClick {
void itemClick(Marcador marcador);
}
}
我希望有人能回答我为什么会发生这种情况，因为我已经检查了其他选项，但我无法真正通过它。
XML 的附加片段：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".fragments.ListaFragment">
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recyler"
android:layout_width="match_parent"
android:layout_height="545dp" />
</LinearLayout>
回收站视图项目的XML附加：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="60dp" android:background="#CDCDCD" android:layout_marginBottom="5dp"
>
<TextView
android:id="@+id/textViewNom"
android:layout_width="410dp"
android:layout_height="55dp"
android:layout_marginLeft="15dp"
android:layout_marginTop="5dp"
android:text="Title"
android:textSize="20sp"
android:textStyle="bold" />
<TextView
android:id="@+id/textViewLatitud"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="15dp"
android:layout_marginTop="35dp"
android:text="latitud" />
<TextView
android:id="@+id/textViewLongitut"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="125dp"
android:layout_marginTop="35dp"
android:text="longitut" />
<ImageView
android:id="@+id/imageView"
android:layout_width="45dp"
android:layout_height="45dp"
android:layout_marginLeft="265dp"
android:layout_marginTop="10dp"
/>
</RelativeLayout>
【问题讨论】：
标签： android android-fragments firebase-realtime-database android-recyclerview firebaseui