notifyDataSetChanged（）; 不刷新ListView？

Question

I'm working on a notes app and I'm running into trouble deleting notes. the problem I'm running into is after the note is deleted, it still shows in the listview. I'm trying to use notifyDataSetChanged(); but it doesn't seem to be working for me :/ i know its probably something I'm doing wrong with my adapter but I'm having trouble narrowing down my mistake as I'm very new to android. any help would be greatly appreciated, thanks in advanced! :D

MainActivity public class MainActivity extends AppCompatActivity {

private ListView mListViewNotes;
ArrayAdapter<Note> listAdapter;
ArrayList<Note> list_items = new ArrayList<>();
int count = 0;
String list_item;
Object mActionMode;
Toolbar app_bar;
ArrayList<Note> notes;
private String mNoteFileName;
private Note mLoadedNote;
Note loadedNote;
ImageView picTest;
NoteAdapter na;

@RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    app_bar = (Toolbar) findViewById(R.id.app_bar);
    TextView title_1 = (TextView) findViewById(R.id.title1);
    TextView title_2 = (TextView) findViewById(R.id.title2);
    TextView title_m = (TextView) findViewById(R.id.title_m);
    Typeface music_font = Typeface.createFromAsset(getAssets(), "fonts/melodymakernotesonly.ttf");
    Typeface notes_font = Typeface.createFromAsset(getAssets(), "fonts/the unseen.ttf");
    setSupportActionBar(app_bar);
    getSupportActionBar().setDisplayShowTitleEnabled(false);
    getSupportActionBar().setElevation(12);
    title_1.setTypeface(music_font);
    title_2.setTypeface(notes_font);
    title_m.setTypeface(music_font);

    listAdapter = new ArrayAdapter<Note>(this, R.layout.item_note, R.id.item_note, list_items);

    mNoteFileName = getIntent().getStringExtra("NOTE_FILE");
    if (mNoteFileName != null && !mNoteFileName.isEmpty()) {
        loadedNote = Utilities.getNoteByName(this, mNoteFileName);
    }

    mListViewNotes = (ListView) findViewById(R.id.listview_notes);
    mListViewNotes.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE_MODAL);
    mListViewNotes.setMultiChoiceModeListener(new AbsListView.MultiChoiceModeListener() {
        @Override
        public void onItemCheckedStateChanged(ActionMode mode, int position, long id, boolean checked) {
            if (list_items.contains(notes.get(position))) {
                count = count-1;
                list_items.remove(notes.get(position));
                mode.setTitle(count + " Notes Selected");
            } else {
                count = count+1;
                list_items.add(notes.get(position));
                mode.setTitle(count + " Notes Selected");
            }

            if (count == 0) {
                mode.setTitle("No Notes Selected");
            }
        }

        @Override
        public boolean onCreateActionMode(ActionMode mode, Menu menu) {

            app_bar.setVisibility(View.GONE);
            MenuInflater inflater = mode.getMenuInflater();
            inflater.inflate(R.menu.context_menu, menu);
            return true;
        }

        @Override
        public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
            return false;
        }

        @Override
        public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
            deleteNote();
            return true;
        }

        @Override
        public void onDestroyActionMode(ActionMode mode) {
            count = 0;
            app_bar.setVisibility(View.VISIBLE);
            list_items.clear();
        }
    });
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.menu, menu);
    return super.onCreateOptionsMenu(menu);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case R.id.add_note:
            startActivity(new Intent(this, NoteActivity.class));
            break;
        case R.id.action_settings:
            Log.d("list:", "testing");
    }

    return true;
}

@Override
protected void onResume() {
    super.onResume();
    mListViewNotes.setAdapter(null);

    notes = Utilities.getAllSavedNotes(this);

    if (notes == null || notes.size() == 0) {
        Toast.makeText(this, "No Notes!", Toast.LENGTH_LONG).show();
    } else {
        na = new NoteAdapter(this, R.layout.item_note, notes);
        mListViewNotes.setAdapter(na);

        mListViewNotes.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                String filename = ((Note) mListViewNotes.getItemAtPosition(position)).getDateTime() + Utilities.FileExtention;

                Intent view_note = new Intent(getApplicationContext(), NoteActivity.class);
                view_note.putExtra("NOTE_FILE", filename);
                startActivity(view_note);
            }
        });
    }
}

private void deleteNote() {

        if(list_items.contains(null)) {
            finish();
        } else {
            AlertDialog.Builder dialog = new AlertDialog.Builder(this)
                    .setTitle("Delete")
                    .setMessage("Are you sure?")
                    .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            for (Note loadedNote : list_items) {
                                Utilities.deleteNote(getApplicationContext(), loadedNote.getDateTime() + Utilities.FileExtention);
                            }
                            na.notifyDataSetChanged();
                            listAdapter.notifyDataSetChanged();
                        }
                    })
                    .setNegativeButton("No", null)
                    .setCancelable(false);
            dialog.show();
        }
}

NoteAdapter

public class NoteAdapter extends ArrayAdapter<Note> {

public NoteAdapter(Context context, int resource, ArrayList<Note> notes) {
    super(context, resource, notes);



}

@Override
public View getView(int position, View convertView, @NonNull ViewGroup parent) {
    //return super.getView(position, convertView, parent);

    if(convertView == null) {
        convertView = LayoutInflater.from(getContext())
                .inflate(R.layout.item_note, null);
    }

    Note note = getItem(position);

    if(note != null) {
        TextView title = (TextView) convertView.findViewById(R.id.list_note_title);
        TextView content = (TextView) convertView.findViewById(R.id.list_note_content);
        TextView date = (TextView) convertView.findViewById(R.id.list_note_date);

        Typeface scribble_card = Typeface.createFromAsset(getContext().getAssets(), "fonts/the unseen.ttf");
        title.setTypeface(scribble_card);
        content.setTypeface(scribble_card);

        title.setText(note.getTitle());
        date.setText(note.getDateTimeFormatted(getContext()));

        if(note.getContent().length() > 25) {
            content.setText(note.getContent().substring(0,25) + "...");
        } else {
            content.setText(note.getContent());
        }

        if(note.getContent().length() <= 0) {
            content.setText("(Empty Note..)");
        } else {
            content.setText(note.getContent());
        }

        if (note.getTitle().length() <= 0) {
            title.setText("(Untitled)");
        } else {
            title.setText(note.getTitle());
        }
    }

    return convertView;
}

Answer 1

You are setting adapter with a list :-

 na = new NoteAdapter(this, R.layout.item_note, notes);
    mListViewNotes.setAdapter(na);

na.notifyDataSetChanged(); will only work if your notes list is changed . And i don't see that you remove/add/modify on notes list. If you are deleting item from list you need to remove it from notes list too See below:-

notes.remove(position_to_remove); na.notifyDataSetChanged();