getting exception ' android.database.CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0'

The application crashes when i click button. with the error android.database.CursorIndexOutOfBoundsException: Index 0 requested, with a size of 0.

This is my: MainActivty.java

public class MainActivity extends AppCompatActivity{
    EditText editText,editText2;
    ListView listView;
    Button button,button2;
    DBHelper dbHelper = new DBHelper(this);
    Cursor cursor = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    populateListView();
    editText = (EditText)findViewById(R.id.editText);
    editText2 = (EditText)findViewById(R.id.editText2);
    button = (Button)findViewById(R.id.button);
    button2 = (Button)findViewById(R.id.button2);
    listView = (ListView)findViewById(R.id.listView);
    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            Cursor mycursor = (Cursor) parent.getItemAtPosition(position);
            String str = mycursor.getString(1);
            Toast.makeText(getBaseContext(),str,Toast.LENGTH_SHORT).show();
            dbHelper.deleteData(str);
            populateListView();
        }
    });
    button2.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            SQLiteDatabase db = dbHelper.getWritableDatabase();
            dbHelper.onUpgrade(db, 1, 2);
            populateListView();
        }
    });
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if(editText.getText().toString().isEmpty() ||editText2.getText().toString().isEmpty()) return;
            Cursor upCursor = dbHelper.getData();
            boolean presence = false;
            if(upCursor!=null) {
                upCursor.moveToFirst();
                do{
                    if(upCursor.getString(1).equals(editText.getText().toString())) presence = true;
                    upCursor.moveToNext();
                }while(!upCursor.isAfterLast());
            }
            else;
            if(presence)
                 dbHelper.updateData(editText.getText().toString(), Integer.parseInt(editText2.getText().toString()));
            else dbHelper.insertActivity(editText.getText().toString(), Integer.parseInt(editText2.getText().toString()));
            populateListView();
        }
    });
private void populateListView(){
    cursor = dbHelper.getData();
    cursor.moveToFirst();
    String[] fromFieldNames = new String[] {dbHelper.ROW_ID,dbHelper.ACTIVITY_TITLE,dbHelper.ACTIVITY_PRIORITY};
    int[] toViewIDs = new int[] {R.id.row_id, R.id.activity_name,R.id.activity_priority};
    if(cursor == null) Toast.makeText(getBaseContext(),"cursor is null",Toast.LENGTH_SHORT).show();
    else
    {
        Toast.makeText(getBaseContext(),"cursor is not null",Toast.LENGTH_SHORT).show();
        SimpleCursorAdapter myCursorAdapter = new SimpleCursorAdapter(getBaseContext(),
                     R.layout.list_layout,cursor,fromFieldNames,toViewIDs,0);
        //listView.setAdapter(myCursorAdapter);
    }
}

}

This is my DBHelper.java class:

public class DBHelper extends SQLiteOpenHelper {

public static final String DATABASE_NAME = "MyDBName.db";
public static final int database_version = 24;
public static final String TABLE_NAME = "list_11";
public static final String ACTIVITY_TITLE = "activity_title";
public static final String ROW_ID = "_id";
public static final String ACTIVITY_PRIORITY = "priority";
public DBHelper(Context context)
{
    super(context, DATABASE_NAME , null, database_version);
}

@Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL(
            "create table list_11 " +
                    "( _id integer primary key autoincrement, activity_title text, priority int )"
    );
    Log.d("DBHelper", "onCreate");
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("DROP TABLE IF EXISTS list_11");
    onCreate(db);
    Log.d("DBHelper", "onUpgrade");
}

public void insertActivity (String name,int a)
{
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put("activity_title", name);
    contentValues.put("priority", a);
    db.insert(TABLE_NAME, null, contentValues);
    Log.d("DBHelper", "one row inserted");
}
public Cursor getData(){
    SQLiteDatabase db = this.getReadableDatabase();
    String[] columns = {ROW_ID,ACTIVITY_TITLE,ACTIVITY_PRIORITY};
    Cursor res = db.query(TABLE_NAME, columns, null, null,null,null,ACTIVITY_PRIORITY+" DESC ");
    return res;
}
public void updateData(String name,int a)
{
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put(ACTIVITY_PRIORITY,a);
    db.update(TABLE_NAME,contentValues,ACTIVITY_TITLE+" = ?",new String[] {name});
}
public void deleteData(String name)
{
    SQLiteDatabase db = this.getWritableDatabase();
    db.delete(TABLE_NAME,ACTIVITY_TITLE+" = ?",new String[] {name});
}

}