我正在尝试在我的安卓项目中使用Cursor Loader
和Custom Cursor Adapter
与数据库(Sqlite本地数据库)进行交互。我希望通过使用Cursor Loader和Adapter异步地从本地数据库中获取数据并向我的listview中填充数据。下面是我的类、子类和方法:
// Home Activity class
public class HomeActivity extends FragmentActivity implements LoaderCallbacks<Cursor> {
DotCursorAdapter mAdapter;
private ListView lv;
private final int LOADER_ID = 1932;
DatabaseHandler dbHelper = new DatabaseHandler(this);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.home_activity);
lv = (ListView) findViewById(R.id.lists);
mAdapter = new DotCursorAdapter(this, null,0);
lv.setAdapter(mAdapter);
getSupportLoaderManager().initLoader(LOADER_ID, null, this);
}
@Override
public Loader<Cursor> onCreateLoader(int i, Bundle bundle) {
return new DumbLoader(this);
}
@Override
public void onLoadFinished(Loader<Cursor> cursorLoader, Cursor cursor) {
mAdapter.swapCursor(cursor);
}
@Override
public void onLoaderReset(Loader<Cursor> cursorLoader) {
mAdapter.swapCursor(null);
}
/**
* DumbLoader sub class
*/
public class DumbLoader extends CursorLoader {
private static final String TAG = "DumbLoader";
public DumbLoader(Context context) {
super(context);
}
@Override
public Cursor loadInBackground() {
Cursor c = dbHelper.fetchAllCountries();
return c;
}
}
/**
* DotCursor Adapter sub class
*/
public final class DotCursorAdapter extends CursorAdapter {
public DotCursorAdapter(Context context, Cursor cursor, int flags) {
super(context, cursor, 0);
}
@Override
public void bindView(View view, Context context, Cursor cursor) {
// Find fields to populate in inflated template
TextView tvBody = (TextView) view.findViewById(R.id.header_text);
String body = cursor.getString(cursor.getColumnIndexOrThrow("fname"));
// Populate fields with extracted properties
tvBody.setText(body);
}
@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
return LayoutInflater.from(context).inflate(R.layout.list_cardview_activity, parent, false);
}
}
}
以下是我的数据库处理程序方法,它从数据库中获取数据。
public Cursor fetchAllCountries() {
SQLiteDatabase db = this.getReadableDatabase();
Cursor mCursor = db.query(TABLE_LOGIN, new String[] {KEY_ID,KEY_FIRSTNAME},
null, null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
问题描述
执行以上代码后,从日志中可以看到出现错误消息并且应用程序崩溃。
主要错误信息如下:
从onCreateLoader返回的对象不应该是非静态内部成员类。
以下是我的日志详细信息:
09-21 16:13:25.563: D/AbsListView(26541): 获取MotionRecognitionManager 09-21 16:13:25.568: D/AndroidRuntime(26541): 关闭 VM 09-21 16:13:25.573: W/dalvikvm(26541): 线程 ID=1: 线程退出,带有未捕获的异常 (group=0x411372a0) 09-21 16:13:25.573: E/AndroidRuntime(26541): 致命错误:主线程 09-21 16:13:25.573: E/AndroidRuntime(26541): java.lang.RuntimeException: 无法启动活动 ComponentInfo{com.alliswell.alliswell/com.alliswell.alliswell.HomeActivity}:java.lang.IllegalArgumentException:从 onCreateLoader 返回的对象不能是非静态内部成员类:DumbLoader{418dc668 id=0} 09-21 16:13:25.573: E/AndroidRuntime(26541): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2110) 09-21 16:13:25.573: E/AndroidRuntime(26541): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2135) 09-21 16:13:25.573: E/AndroidRuntime(26541): at android.app.ActivityThread.access$700(ActivityThread.java:140) 09-21 16:13:25.573: E/AndroidRuntime(26541): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1237) 09-21 16:13:25.573: E/AndroidRuntime(26541): at android.os.Handler.dispatchMessage(Handler.java:99) 09-21 16:13:25.573: E/AndroidRuntime(26541): at android.os.Looper.loop(Looper.java:137) 09-21 16:13:25.573: E/AndroidRuntime(26541): at android.app.ActivityThread.main(ActivityThread.java:4921) 09-21 16:13:25.573: E/AndroidRuntime(26541): at java.lang.reflect.Method.invokeNative(Native Method) 09-21 16:13:25.573: E/AndroidRuntime(26541): at java.lang.reflect.Method.invoke(Method.java:511) 09-21 16:13:25.573: E/AndroidRuntime(26541): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038) 09-21 16:13:25.573: E/AndroidRuntime(26541): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805) 09-21 16:13:25.573: E/AndroidRuntime(26541): at dalvik.system.NativeStart.main(Native Method) 09-21 16:13:25.573: E/AndroidRuntime(26541): Caused by: java.lang.IllegalArgumentException:从 onCreateLoader 返回的对象不能是非静态内部成员类:DumbLoader{418dc668 id=0} 09-21 16:13:25.573: E/AndroidRuntime(26541): at android.support.v4.app.LoaderManagerImpl$LoaderInfo.start(LoaderManager.java:257) 09-21 16:13:25.573: E/AndroidRuntime(26541): at android.support.v4.app.LoaderManagerImpl.doStart(LoaderManager.java:714) 09-21 16:13:25.573: E/AndroidRuntime(26541): at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:556) 09-21 16:13:25.573: E/AndroidRuntime(26541): at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1178) 09-21 16:13:25.573: E/AndroidRuntime(26541): at android.app.Activity.performStart(Activity.java:5198) 09-21 16:13:25.573: E/AndroidRuntime(26541): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2083) 09-21 16:13:25.573: E/AndroidRuntime(26541): …11 more我认为我的代码存在问题,如果有人能帮助我解决这个问题,我将不胜感激。谢谢。