How to update data in Recycler view?

Question

My Recycler view does not update when I add or remove a new item to it. How do I fix that?

I looked at this question here, which seems to have all the answers but they are not working for me --> link

code:

public void createPlaylist() {
        dialog.setContentView(R.layout.add_playlist);
        final TextView Playlist_name = dialog.findViewById(R.id.Playlist_name);
        Button CreateButton = dialog.findViewById(R.id.CreateButton);
        CreateButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String text = Playlist_name.getText().toString().trim();
                if (TextUtils.isEmpty(text)) {
                    Playlist_name.requestFocus();
                    Playlist_name.setError("Please fill in this field");
                } else {
                    boolean inserted = db.addPlaylist(text); // **How do I update the playlist after its added to the db??**
                    if (inserted) {
                        Toast.makeText(getContext(), "Playlist created!", Toast.LENGTH_SHORT).show();
                    } else {
                        Toast.makeText(getContext(), "Playlist isn't created :(", Toast.LENGTH_SHORT).show();
                    }
                    dialog.dismiss();
                }
            }
        });
        dialog.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
        dialog.show();
    }

CODE: This is within my viewholder insinde my Custom Adapter class

holder.popupMenu.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                PopupMenu popupMenu = new PopupMenu(context, v);
                popupMenu.inflate(R.menu.popup_menu);
                popupMenu.show();

                popupMenu.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
                    @Override
                    public boolean onMenuItemClick(MenuItem item) {
                        switch (item.getItemId()) {
                            case R.id.delete:
                                AlertDialog.Builder dialog = new AlertDialog.Builder(context, R.style.DialogStyle);
                                dialog.setTitle("Delete Playlist")
                                        .setMessage("Are you sure you want to delete this playlist?")
                                        .setPositiveButton("Delete", new DialogInterface.OnClickListener() {
                                            @Override
                                            public void onClick(DialogInterface dialog, int which) {
                                                db.deletePlaylist(array_list.get(position).getPlaylistName()); **//How do I update the recycler after deleting ???**
                                                Toast.makeText(context, "Deleted", Toast.LENGTH_SHORT).show();
                                            }
                                        }).setNegativeButton("Cancel", null);
                                dialog.create().show();
                                return true;
                            default:
                                return false;
                        }
                    }
                });
            }
        });