光标适配器用于在ListView中填充TextView和ToggleButton

Question

我在活动类中实现了以下代码。同时，该应用程序在启动它时崩溃。

我缺少什么？

public class MainActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<Object> {
private ListView obj;
DBHelper mydb;
SimpleCursorAdapter dataAdapter;
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Cursor rs = mydb.getAllAlarms();
    startManagingCursor(rs);
    String[] from = new String[]{"name"};
    int[] to = new int[]{R.id.alarm_name};
    dataAdapter = new SimpleCursorAdapter(this, R.layout.listview_row, rs, from, to, 0);
obj = (ListView)findViewById(R.id.listViewAlarms);
obj.setAdapter(dataAdapter);
getSupportLoaderManager().initLoader(0, null, this);
    obj.setOnItemClickListener(new OnItemClickListener(){
        @Override
        public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                                long arg3) {
            //obj.getItemAtPosition(arg2);
            // TODO Auto-generated method stub
            String itemVal =(String) arg0.getItemAtPosition(arg2);
            Bundle dataBundle = new Bundle();
            dataBundle.putString("name", itemVal);
            Intent intent = new
                    Intent(getApplicationContext(),DisplayAlarm.class);
            intent.putExtras(dataBundle);
            startActivity(intent);
        }
    });
}

Answer 1

您尚未将光标放入适配器中。从此更改您的代码

dataAdapter = new SimpleCursorAdapter(getBaseContext(), R.layout.listview_row,
            null, new String[] { mydb.ALARMS_COLUMN_NAME, mydb.ALARMS_ACTIVATED},
            new int[] { R.id.alarm_name, R.id.alarm_activated }, 0);

to

dataAdapter = new SimpleCursorAdapter(getBaseContext(), R.layout.listview_row,
            rs, new String[] { mydb.ALARMS_COLUMN_NAME, mydb.ALARMS_ACTIVATED},
            new int[] { R.id.alarm_name, R.id.alarm_activated }, 0);

另外，只需传递列名，而不是使用mydb.ALARMS_COLUMN_NAME, mydb.ALARMS_ACTIVATED。