小编Rau*_*dey的帖子

我想从表格中检索特定的单元格。我想要 alarm_music(TEXT)，其中我将警报的小时数（整数）和分钟数（整数）（在 where 子句中）存储在警报表中。
触发查询的代码

mBhelperClass = new AlarmsDBhelperClass(this);
        db= mBhelperClass.getWritableDatabase();
        Cursor cursor = db.rawQuery("SELECT musicPath FROM alarms WHERE hours="+hour+" AND minutes="+min,null);
        Log.d("gaurnagSnooze",""+cursor.getCount());
        if (cursor.moveToFirst()) {
            songPath = cursor.getString(cursor.getColumnIndex(AlarmsDBhelperClass.MUSIC_PATH));
            Log.d("if executed! ","songpath initialized!");
        }
        cursor.close();

moveToFirst() 返回 FALSE 意味着表中没有行。
但是当我触发SELECT musicPath FROM alarmsmoveToFirst() 时返回TRUE。
这怎么可能？

我正在使用 RecyclerView 并从数据库中填充数据并将其存储到 arrayLists 中。我还在回收器视图中添加了一个 onLongClickListener()，它删除了长按的行。一切正常，但是当我删除最后一个应用程序崩溃时，我得到 Java.Lang.IndexOutOfBoundsException index:0 size:0。

这是我的代码

public class MainActivity extends AppCompatActivity implements AlarmRecyclerViewInterface {

    FloatingActionButton mAlarmAddButton;
    RecyclerView mRecyclerView;
    SQLiteDatabase db;
    AlarmsDBhelperClass mAlarmsDBhelperClass;
    ArrayList<String> nameArrayList = new ArrayList<>();
    ArrayList <String> modeArrayList = new ArrayList<>();
    ArrayList<String> repeatArrayList = new ArrayList<>();
    ArrayList<String> hoursArrayList = new ArrayList<>();
    ArrayList<String> minArrayList = new ArrayList<>();
    Switch mSwitch;
    AlarmAdapter alarmAdapter = new AlarmAdapter(hoursArrayList,minArrayList,modeArrayList,repeatArrayList,nameArrayList,this);
    ImageView emptyImageView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);

        //Initializing RecyclerView, DatabaseHelperClass, FAB button, The ON OFF switch & …