削除確認ダイアログを使って削除した際のリストを更新する方法を知りたい

前提・実現したいこと

Android Studioでtodoアプリのようなものを作っています。

MainActivityにリスト一覧が表示されていて、リストの要素を長押しした時に、削除の確認ダイアログが出て、OKがクリックされた時に削除する流れを作ったのですが、削除した後リスト一覧を更新したいのですが、それができず困っています。

削除した後リスト一覧を更新する方法を教えていただきたいです。

該当のソースコード

コードは質問に関連する部分だけを抜粋しています。

MainActivity:

Java
1public class MainActivity extends AppCompatActivity {
2　　@Override
3    protected void onResume() {
4        super.onResume();
5
6        selectDb();
7    }
8　　public void selectDb() {
9        _helper = new DatabaseHelper(MainActivity.this);
10
11        SQLiteDatabase db = _helper.getWritableDatabase();
12
13        String[] projection = {
14                DatabaseContract._ID,
15                DatabaseContract.COLUMN_NAME_TITLE,
16        };
17
18        _cursor = db.query(
19                DatabaseContract.TABLE_NAME,
20                projection,
21                null,
22                null,
23                null,
24                null,
25                null
26        );
27
28        AACursorAdapter _adapter = new AACursorAdapter(MainActivity.this, _cursor);
29
30        ListView lvMemo = findViewById(R.id.lvMemo);
31
32        lvMemo.setAdapter(_adapter);
33
34        lvMemo.setOnItemClickListener(new ListItemClickListener());
35
36        lvMemo.setOnItemLongClickListener(new ListItemLongClickListener());
37    }
38
39    private class ListItemClickListener implements AdapterView.OnItemClickListener{
40        @Override
41        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
42        }
43    }
44
45    private class ListItemLongClickListener implements AdapterView.OnItemLongClickListener {
46        @Override
47        public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
48            DeleteConfirmDialogFragment dialogFragment = new DeleteConfirmDialogFragment();
49
50            _cursor = (Cursor) parent.getItemAtPosition(position);
51            int memoId = _cursor.getInt(0);
52            String memoTitle = _cursor.getString(1);
53
54            int main = -3;
55
56            Bundle args = new Bundle();
57            args.putString("memoTitle", memoTitle);
58            args.putInt("memoId", memoId);
59
60            args.putInt("activity", main);
61
62            dialogFragment.setArguments(args);
63
64            dialogFragment.show(getSupportFragmentManager(), "DeleteConfirmDialogFragment");
65            return true;
66        }
67    }
68}

AACursorAdapter:

Java
1public class AACursorAdapter extends CursorAdapter {
2
3    private LayoutInflater mInflater;
4
5    public AACursorAdapter(Context context, Cursor cursor) {
6        super(context, cursor);
7
8        mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
9    }
10
11    static class ViewHolder {
12        TextView title;
13    }
14
15    @Override
16    public View newView(Context context, Cursor cursor, ViewGroup viewGroup) {
17        View view = mInflater.inflate(R.layout.memo_list_item, null);
18
19        ViewHolder holder = new ViewHolder();
20        holder.title = (TextView) view.findViewById(R.id.tvTitle);
21    
22        view.setTag(holder);
23
24        return view;
25    }
26
27    @Override
28    public void bindView(View view, Context context, Cursor cursor) {
29        ViewHolder holder = (ViewHolder) view.getTag();
30
31        int memoId = cursor.getInt(0);
32        String memoTitle = cursor.getString(1);
33       
34        holder.title.setText(memoTitle);
35    }
36
37}

DeleteConfirmDialogFragment:

Java
1public class DeleteConfirmDialogFragment extends DialogFragment {
2
3    String _memoTitle;
4    int _memoId;
5    int _activity;
6
7    Activity _parentActivity;
8
9    @Override
10    public Dialog onCreateDialog(Bundle savedInstanceState){
11        _memoTitle = getArguments().getString("memoTitle", "");
12        _memoId = getArguments().getInt("memoId", -1);
13
14        _activity = getArguments().getInt("activity", 0);
15
16
17        AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
18
19        String message = _memoTitle + getString(R.string.dialog_msg_delete);
20
21        builder.setTitle(R.string.dialog_title_delete);
22        builder.setMessage(message);
23        builder.setPositiveButton(R.string.dialog_btn_ok, new DialogButtonClickListener());
24        builder.setNegativeButton(R.string.dialog_btn_ng, new DialogButtonClickListener());
25
26        AlertDialog dialog = builder.create();
27        return dialog;
28    }
29
30    private class DialogButtonClickListener implements DialogInterface.OnClickListener {
31        @Override
32        public void onClick(DialogInterface dialog, int which) {
33            String msg = "";
34
35            switch (which){
36                case DialogInterface.BUTTON_POSITIVE:
37                    delete();
38                    msg = _memoTitle + getString(R.string.dialog_ok_delete_toast);
39
40                    if (_activity == -5){
41                        _parentActivity.finish();
42                    } else if(_activity == -3) {
43                        //_parentActivity.
44                    }
45
46                    break;
47                case DialogInterface.BUTTON_NEGATIVE:
48                    msg = getString(R.string.dialog_ng_delete_toast);
49                    break;
50            }
51
52            Toast.makeText(getActivity(), msg, Toast.LENGTH_LONG).show();
53        }
54    }
55
56    public void delete() {
57        _parentActivity = getActivity();
58
59        DatabaseHelper helper = new DatabaseHelper(_parentActivity);
60
61        try (SQLiteDatabase db = helper.getWritableDatabase()){
62            db.delete(DatabaseContract.TABLE_NAME,
63                    DatabaseContract._ID + " = ? ",
64                    new String[] {String.valueOf(_memoId)});
65        }
66    }
67}

jimbe

2021/10/23 13:56

肝心の"リスト一覧"に関する部分が必要です。

行動規範の内容に同意します

回答2件

自己解決

MainActivity:

java
1public class MainActivity extends AppCompatActivity implements DeleteConfirmDialogFragment.DeleteConfirmDialogFragmentListener {
2
3~省略~
4
5    private class ListItemLongClickListener implements AdapterView.OnItemLongClickListener {
6        @Override
7        public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
8            DeleteConfirmDialogFragment dialogFragment = new DeleteConfirmDialogFragment();
9
10            _cursor = (Cursor) parent.getItemAtPosition(position);
11            int memoId = _cursor.getInt(0);
12            String memoTitle = _cursor.getString(1);
13
14            int main = -3;
15
16            Bundle args = new Bundle();
17            args.putString("memoTitle", memoTitle);
18            args.putInt("memoId", memoId);
19
20            args.putInt("activity", main);
21
22            dialogFragment.setArguments(args);
23
24            dialogFragment.show(getSupportFragmentManager(), "DeleteConfirmDialogFragment");
25
26            return true;
27        }
28    }
29
30    public void onDialogFragmentResult() {
31
32        SQLiteDatabase db = _helper.getWritableDatabase();
33
34        String[] projection = {
35                DatabaseContract._ID,
36                DatabaseContract.COLUMN_NAME_TITLE,
37        };
38
39
40        _cursor = db.query(
41                DatabaseContract.TABLE_NAME,
42                projection,
43                null,
44                null,
45                null,
46                null,
47                null
48        );
49
50        _adapter.changeCursor(_cursor);
51        _adapter.notifyDataSetChanged();
52    }
53}

DeleteConfirmDialogFragment:

java
1public class DeleteConfirmDialogFragment extends DialogFragment {
2
3    private DeleteConfirmDialogFragmentListener _listener;
4
5    public interface DeleteConfirmDialogFragmentListener {
6        void onDialogFragmentResult();
7    }
8
9
10~省略~
11
12    private class DialogButtonClickListener implements DialogInterface.OnClickListener {
13        @Override
14        public void onClick(DialogInterface dialog, int which) {
15            String msg = "";
16
17            _parentActivity = getActivity();
18
19            switch (which){
20                case DialogInterface.BUTTON_POSITIVE:
21                    delete();
22                    msg = _memoTitle + getString(R.string.dialog_ok_delete_toast);
23
24                    if (_activity == -5){
25                        _parentActivity.finish();
26                    } else if(_activity == -3) {
27                        _listener = (DeleteConfirmDialogFragmentListener) _parentActivity;
28                        _listener.onDialogFragmentResult();
29                    }
30                    break;
31                case DialogInterface.BUTTON_NEGATIVE:
32                    msg = getString(R.string.dialog_ng_delete_toast);
33                    break;
34            }
35
36            Toast.makeText(getActivity(), msg, Toast.LENGTH_LONG).show();
37        }
38    }
39}