从onCreateLoader返回的对象不能是非静态内部成员类:DumbLoader

Question

我试图在我的android项目中实现Cursor Loader和Custom Cursor Adapter数据库(Sqlite本地数据库).我实际上想借助Cursor Loader和Adapter`将我的listview与本地数据库中的数据异步提供.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);
              }
            }
    }

下面还有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 在上面执行此代码时,会从日志cat中发出消息错误并将应用程序包含在内.

主要错误

从onCreateLoader返回的对象不能是非静态内部成员类

下面也是我的日志猫详情

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):threadid = 1:线程退出,未捕获异常(组= 0x411372a0)09-21 16:13:25.573:E/AndroidRuntime(26541):致命异常:主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):在android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2135)09-21 16:13:25.573:E/AndroidRuntime(26541):在android.app.ActivityThread.access $ 700(ActivityThread.java:140)09-21 16:13:25.573:E/AndroidRuntime(26541):在android.app.ActivityThread $ H.handleMessage(ActivityThread.java:1237)09-21 16:13:25.573:E/AndroidRuntime(26541):在android.os.Handler.dispatchMessage(Handler. java:99)09-21 16:13:25.573:E/AndroidRuntime(26541):在android.os.Looper.loop(Looper.java:137)09-21 16:13:25.573:E/AndroidRuntime(26541) :在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):在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):引起: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):在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):在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):在android.app.Activity.performStart(Activity.java:5198)09-21 16:13:25.573:E/AndroidRuntime(26541):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java) :2083)09-21 16:13:25.573:E/AndroidRuntime(26541):... 11更多performLaunchActivity(ActivityThread.java:2083)09-21 16:13:25.573:E/AndroidRuntime(26541):... 11更多performLaunchActivity(ActivityThread.java:2083)09-21 16:13:25.573:E/AndroidRuntime(26541):... 11更多

我认为我在我的代码中做错了什么,如果有人能帮我解决这个问题,我将不胜感激.谢谢.

Answer 1

你有2种方法来解决这个问题:

1.-创建DumbLoader.java文件并将其设置如下:

public class DumbLoader extends CursorLoader {

     private DatabaseHandler mDBHelper;

     public DumbLoader(Context context, DatabaseHandler dbHelper) {
         super(context);
         mDBHelper = dbHelper;
     }

     @Override
     public Cursor loadInBackground() {
         return mDBHelper.fetchAllCountries();
     }
}

2.- static为Activity的DumbLoader嵌套类使用修饰符,使其如下所示:

public class HomeActivity extends FragmentActivity implements LoaderCallbacks<Cursor> {

    //onCreate(), etc...

    //Make DumbLoader nested class STATIC
    public static class DumbLoader extends CursorLoader {

        private DatabaseHandler mDBHelper;

        public DumbLoader(Context context, DatabaseHandler dbHelper) {
            super(context);
            mDBHelper = dbHelper;
        }

        @Override
        public Cursor loadInBackground() {
            return mDBHelper.fetchAllCountries();
        }
}