Android app crashes upon removing an item from FirebaseRecyclerAdapter

Question

I created a remove function in the populateViewHolder like so:

viewHolder.mView.setOnLongClickListener(new View.OnLongClickListener() {
    @Override
    public boolean onLongClick(View v) {
        new AlertDialog.Builder(getContext())
                .setTitle("Are you sure?")
                .setMessage("Do you want to delete this note?")
                .setPositiveButton("Yes", new DialogInterface.OnClickListener()
                {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        mNotesDatabase.child(list_id).removeValue();
                        notifyDataSetChanged();
                        notifyItemRemoved(position);
                    }
                })
                .setNegativeButton("No", null)
                .show();

        return true;
    }
});

This code is present in: public void onDataChange(DataSnapshot dataSnapshot). When I run my code and try to remove the item from the list, my app crashes. However, it does remove the item in the database itself. I think my app is not updating the FirebaseRecycleAdapter correctly. I tried using notifydatasetchanged(), which resulted in nothing. I also tried to override onChildRemoved. However onChildRemoved appears to not be a function inside FirebaseRecycleAdapter. I also tried to call the FirebaseRecycleAdapter itself, on which it told me it was not initialized.

Here is the logCat:

edit

Below this text you can find the code for the whole adapter as requested:

        final FirebaseRecyclerAdapter<Notes, NotesViewHolder> notesRecyclerViewAdapter = new FirebaseRecyclerAdapter<Notes, NotesViewHolder>(
            Notes.class,
            R.layout.feed_note_single_layout,
            NotesViewHolder.class,
            mNotesDatabase
    ) {

        @Override
        protected void populateViewHolder(final NotesViewHolder viewHolder, Notes model, final int position) {

            final String list_id = getRef(position).getKey();

            mNotesDatabase.child(list_id).addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    final String title = dataSnapshot.child("title").getValue().toString();
                    final String message = dataSnapshot.child("message").getValue().toString();

                    viewHolder.setTitle(title);
                    viewHolder.setMessage(message);

                    viewHolder.mView.setOnClickListener(new View.OnClickListener() {
                        @Override
                        public void onClick(View v) {
                            Intent noteIntent = new Intent(getContext(), NotesActivity.class);
                            noteIntent.putExtra("list_id", list_id);
                            noteIntent.putExtra("title", title);
                            noteIntent.putExtra("message", message);
                            startActivity(noteIntent);

                        }
                    });

                    viewHolder.mView.setOnLongClickListener(new View.OnLongClickListener() {
                        @Override
                        public boolean onLongClick(View v) {
                            new AlertDialog.Builder(getContext())
                                    .setTitle("Are you sure?")
                                    .setMessage("Do you want to delete this note?")
                                    .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                                        @Override
                                        public void onClick(DialogInterface dialog, int which) {



                                            mNotesDatabase.child(list_id).removeValue();
                                            notifyItemRemoved(viewHolder.getAdapterPosition());
                                            notifyDataSetChanged();


                                        }
                                    })
                                    .setNegativeButton("No", null)
                                    .show();

                            return true;
                        }
                    });

                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });
        }
    };

    mFeedList.setAdapter(notesRecyclerViewAdapter);

What value does your `mNotesDatabase` have? Please add your code regarding `mNotesDatabase`. — Alex Mamo, Nov 21 '17 at 10:35
refer this: https://stackoverflow.com/questions/36252478/how-to-remove-items-from-firebase-recyclerview — Grishma Ukani, Nov 21 '17 at 10:36
post your NotesActivity class's code where this crash is occuring i.e. at line: 201 — Sara Tirmizi, Nov 21 '17 at 10:37
check null on `dataSnapshot` before calling `dataSnapshot.child("title").getValue().toString();` — akhilesh0707, Nov 21 '17 at 10:54
you are getting nullpointer while getting value `title and message` inside datachange — akhilesh0707, Nov 21 '17 at 10:56
I have added a if statement with datasnapshot.exists(). Yet the app still crashes with the same error — 2hTu2, Nov 21 '17 at 11:00

Boonya Kitpitak · Accepted Answer · 2017-11-22T02:31:57.263

1

I think the problem might occur because when you delete the data in RecyclerView and call notifyDataSetChanged(). The position in populateViewHolder might refer to the deleted position.

Therefore, you should use viewHolder.getAdapterPosition() instead of position.

According to the log, the issue might also cause from onDataChange in NoteActivity please carefully check it.

Hope, it's help.

edited Nov 22 '17 at 02:31

answered Nov 21 '17 at 10:44

Boonya Kitpitak

3,607
1
30
30

Did you change all `position` to `viewHolder.getAdapterPosition()` ? including this line `final String list_id = getRef(position).getKey();` – Boonya Kitpitak Nov 21 '17 at 10:55
Just replaced the list_id. Yet it still crashes with the same error – 2hTu2 Nov 21 '17 at 11:01
to be `final String list_id = getRef(itemView.getAdapterPosition()).getKey();` ? – Boonya Kitpitak Nov 21 '17 at 11:03
`final String list_id = getRef(viewHolder.getAdapterPosition()).getKey();` – 2hTu2 Nov 21 '17 at 11:04
Then the problem might be in the `NoteActivity` please post the code of `onDataChange` in that Activity – Boonya Kitpitak Nov 21 '17 at 11:25
Thats it! the onDataChange in NotesActivity was not updated with a datasnapshot.exist(). I can now succesfully delete items from the list without crashes – 2hTu2 Nov 21 '17 at 11:40

score 1 · Answer 2 · answered Nov 21 '17 at 10:44

1

call notifyDataSetChanged() after removing the item like below

 mNotesDatabase.child(list_id).removeValue();

 notifyItemRemoved(position);
 notifyDataSetChanged();

answered Nov 21 '17 at 10:44

Jay Dwivedi

454
3
15

Android app crashes upon removing an item from FirebaseRecyclerAdapter

2 Answers2