notifyItemRemoved（）;直到我退出并重新进入活动才从列表中删除评论

Question

我正在尝试更新评论列表，并且通过使用notifyItemInserted和notifyItemRemoved来进行更新。当用户添加评论时，评论会完美地添加到列表中，但是当我要删除评论时会出现问题。我遇到的问题是，当我删除列表中的注释时，它不仅会立即删除注释，还会重新排列列表，并且仅当我退出活动然后重新输入时才删除注释。

有人可以告诉我如何调整代码，以便立即删除注释吗？

CommentsActivity

public class CommentsActivity extends AppCompatActivity {

    private CommentAdapter mCommentAdapter;
    private List<Comment> mCommentList;
    private RecyclerView mRecyclerView;

    FirebaseUser mFirebaseUser;

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

        mRecyclerView = findViewById(R.id.recycler_view);
        mRecyclerView.setHasFixedSize(true);
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
        mRecyclerView.setLayoutManager(linearLayoutManager);
        mCommentList = new ArrayList<>();
        mCommentAdapter = new CommentAdapter(this, mCommentList, mPostId);
        mRecyclerView.setAdapter(mCommentAdapter);

        mAddComment = findViewById(R.id.add_comment);
        mImageProfile = findViewById(R.id.image_profile);
        mPost = findViewById(R.id.post_comment);

        getImage();
        readComments();
    }

    private void readComments() {
        DatabaseReference reference = FirebaseDatabase.getInstance().getReference("Comments").child(mPostId);
        ChildEventListener childEventListener = new ChildEventListener() {
            @Override
            public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
                Comment comment = dataSnapshot.getValue(Comment.class);
                mCommentList.add(comment);
                mCommentAdapter.notifyItemInserted(mCommentList.size() - 1);

            }

            @Override
            public void onChildChanged(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {

            }

            @Override
            public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {
                Comment comment = dataSnapshot.getValue(Comment.class);

                int position = mCommentList.indexOf(comment);

                mCommentList.remove(comment);
                mCommentAdapter.notifyItemRemoved(position);
                mCommentAdapter.notifyItemRangeChanged(position, mCommentList.size());
            }

            @Override
            public void onChildMoved(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {

            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        };

        reference.addChildEventListener(childEventListener);
    }
}

Answer 1

具有存储项键的列表

public class CommentsActivity extends AppCompatActivity {

private CommentAdapter mCommentAdapter;
private List<Comment> mCommentList;
//add this
private List<String> keysList = new ArrayList<String>();
private RecyclerView mRecyclerView;
............

在添加评论的同时添加密钥：

@Override
public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
Comment comment = dataSnapshot.getValue(Comment.class);
mCommentList.add(comment);

//add this
keysList.add(dataSnapshot.getKey());

mCommentAdapter.notifyItemInserted(mCommentList.size() - 1);
}

现在删除时：

@Override
public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {

int index = keysList.indexOf(dataSnapshot.getKey());

mCommentList.remove(index);
keysList.remove(index);



}