必须在Adapter中将类''从FirebaseAdapter派生的匿名类'声明为abstract

Question

我一直在收到一个错误（在我的FirebaseRecyclerAdapter中），说该类必须在'Adapter'中声明为abstract或实现方法'onCreateViewHolder（ViewGroup，int），以及Method不会覆盖下面“Override”上的超类那段代码。

但是，我不知道如何更改我的代码以摆脱该错误。有人可以帮帮我吗？我真的很感激帮助。谢谢！

DiaryActivity.java package com.shiminu1521462c.fyp_2;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.GridLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.content.Context;
import android.content.Intent;
import android.content.res.Resources;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;

import com.firebase.ui.database.FirebaseRecyclerAdapter;
import com.firebase.ui.database.FirebaseRecyclerOptions;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.Query;
import com.google.firebase.database.ValueEventListener;

public class DiaryActivity extends AppCompatActivity {

    private FirebaseAuth mAuth;
    private DatabaseReference fNotesDatabase;

    private RecyclerView mNotesList;
    private GridLayoutManager gridLayoutManager;
    private DatabaseReference noteRef;


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


        mNotesList = (RecyclerView) findViewById(R.id.notes_list);
        gridLayoutManager = new GridLayoutManager(this, 2, GridLayoutManager.VERTICAL, false);

        mNotesList.setHasFixedSize(true);
        mNotesList.setLayoutManager(gridLayoutManager);
        mNotesList.addItemDecoration(new GridSpacingDecoration(2, dpToPx(10), true));


        mAuth = FirebaseAuth.getInstance();

        if (mAuth.getCurrentUser() != null) {
            fNotesDatabase = FirebaseDatabase.getInstance().getReference().child("Notes").child(mAuth.getCurrentUser().getUid());
        }
        loadData();
    }

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

    }

    private void loadData() {
        Query query = fNotesDatabase.orderByValue();
        FirebaseRecyclerAdapter<NoteModel, NoteViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<NoteModel, NoteViewHolder>(

                NoteModel.class,
                R.layout.single_note_layout,
                NoteViewHolder.class,
                query

        ) {
            @Override
            protected void populateViewHolder(final NoteViewHolder viewHolder, NoteModel model, int position) {
                final String noteId = getRef(position).getKey();

                fNotesDatabase.child(noteId).addValueEventListener(new ValueEventListener() {
                    @Override
                    public void onDataChange(DataSnapshot dataSnapshot) {
                        if (dataSnapshot.hasChild("title") && dataSnapshot.hasChild("timestamp")) {
                            String title = dataSnapshot.child("title").getValue().toString();
                            String timestamp = dataSnapshot.child("timestamp").getValue().toString();

                            viewHolder.setNoteTitle(title);
                            //viewHolder.setNoteTime(timestamp);

                            GetTimeAgo getTimeAgo = new GetTimeAgo();
                            viewHolder.setNoteTime(getTimeAgo.getTimeAgo(Long.parseLong(timestamp), getApplicationContext()));

                            viewHolder.noteCard.setOnClickListener(new View.OnClickListener() {
                                @Override
                                public void onClick(View view) {
                                    Intent intent = new Intent(DiaryActivity.this, DiaryNewNoteActivity.class);
                                    intent.putExtra("noteId", noteId);
                                    startActivity(intent);
                                }
                            });
                        }

                    }

                    @Override
                    public void onCancelled(DatabaseError databaseError) {

                    }
                });

            }
        };
        mNotesList.setAdapter(firebaseRecyclerAdapter);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        super.onCreateOptionsMenu(menu);

        getMenuInflater().inflate(R.menu.diary_menu, menu);

        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        super.onOptionsItemSelected(item);

        switch (item.getItemId()) {
            case R.id.new_note_button:
                Intent newIntent = new Intent(DiaryActivity.this, DiaryNewNoteActivity.class);
                startActivity(newIntent);
                break;
        }

        return true;
    }


    /**
     * Converting dp to pixel
     */
    private int dpToPx(int dp) {
        Resources r = getResources();
        return Math.round(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp, r.getDisplayMetrics()));
    }
}

Answer 1

com.firebase.ui.database.FirebaseRecyclerAdapter是抽象的。

如果你想扩展它（就像你在方法loadData()中使用匿名类一样），你必须实现它的所有抽象方法。在那种情况下显然onCreateViewHolder(ViewGroup, int)。

将此方法实现添加到您的匿名类，您就完成了。