英文:
How to implement RecyclerView to Fragment of BottomNavigationBar?
问题
我不知道如何将 ***RecyclerView*** 实现到片段中。首先,我开始解释我的代码。
public class HomeFragment extends Fragment {
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_home, container, false);
    }
}
所以 `HomeFragment` 应该打开 `fragment_home.xml`,它看起来像这样...
        <androidx.constraintlayout.widget.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".NoteActivity">
    
       <TextView
           android:id="@+id/textView4"
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
           android:layout_marginTop="356dp"
           android:layout_marginEnd="152dp"
           android:text="主页片段"
           android:textColor="#000000"
           app:layout_constraintEnd_toEndOf="parent"
           app:layout_constraintTop_toTopOf="parent" />
    
       <androidx.recyclerview.widget.RecyclerView
           android:id="@+id/recycler_view"
           android:layout_width="match_parent"
           android:layout_height="match_parent"
           tools:layout_editor_absoluteX="0dp"
           tools:layout_editor_absoluteY="16dp" />
    
    
    </androidx.constraintlayout.widget.ConstraintLayout>
是的,它正在打开这个布局 ***但是*** 没有 ***RecyclerView***(TextView 是正常的)。我在思考为什么会发生这种情况,我得出结论,我必须将下面的 `this class`(下面的代码)实现到我的 `HomeFragment` 中(或者只需连接它,同样我不知道如何)
public class NoteActivity extends AppCompatActivity {
    private FirebaseFirestore db = FirebaseFirestore.getInstance();
    private CollectionReference notebookRef = db.collection("Notebook");
    
    private NoteAdapter adapter;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.fragment_home);
    
        setUpRecyclerView();
    }
    
    public void setUpRecyclerView() {
        Query query = notebookRef.orderBy("title", Query.Direction.DESCENDING);
    
        FirestoreRecyclerOptions<Note> options = new FirestoreRecyclerOptions.Builder<Note>()
                .setQuery(query, Note.class)
                .build();
    
        adapter = new NoteAdapter(options);
    
        RecyclerView recyclerView = findViewById(R.id.recycler_view);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setAdapter(adapter);
    }
    
    @Override
    protected void onStart() {
        super.onStart();
        adapter.startListening();
    }
    
    @Override
    protected void onStop() {
        super.onStop();
        adapter.stopListening();
    }
}
请帮忙,谢谢 :)
英文:
I don't know how to implement RecyclerView to fragment. First I start to explain my code.
public class HomeFragment extends Fragment {
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_home, container, false);
    }
} 
So HomeFragment should open fragment_home.xml which look like this...
    <androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".NoteActivity">
   <TextView
       android:id="@+id/textView4"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:layout_marginTop="356dp"
       android:layout_marginEnd="152dp"
       android:text="Home fragment"
       android:textColor="#000000"
       app:layout_constraintEnd_toEndOf="parent"
       app:layout_constraintTop_toTopOf="parent" />
   <androidx.recyclerview.widget.RecyclerView
       android:id="@+id/recycler_view"
       android:layout_width="match_parent"
       android:layout_height="match_parent"
       tools:layout_editor_absoluteX="0dp"
       tools:layout_editor_absoluteY="16dp" />
</androidx.constraintlayout.widget.ConstraintLayout>
and yes it is opening this layout BUT without RecyclerView (TextView is OK).
I was thinking why it's happening and I came to the conclusion that I have to implement this class (down below) to my HomeFragment (or just connect that, again I don't know how)
public class NoteActivity extends AppCompatActivity {
    private FirebaseFirestore db = FirebaseFirestore.getInstance();
    private CollectionReference notebookRef = db.collection("Notebook");
    private NoteAdapter adapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.fragment_home);
        setUpRecyclerView();
    }
    public void setUpRecyclerView() {
        Query query = notebookRef.orderBy("title", Query.Direction.DESCENDING);
        FirestoreRecyclerOptions<Note> options = new FirestoreRecyclerOptions.Builder<Note>()
                .setQuery(query, Note.class)
                .build();
        adapter = new NoteAdapter(options);
        RecyclerView recyclerView = findViewById(R.id.recycler_view);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setAdapter(adapter);
    }
    @Override
    protected void onStart() {
        super.onStart();
        adapter.startListening();
    }
    @Override
    protected void onStop() {
        super.onStop();
        adapter.stopListening();
    }
}
Please help, thanks ![]()
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