使用cursorloader填充时，为什么我的listview如此暗淡？

Question

经过大量的工作，我终于使用CursorLoader和SimpleCursorAdapter填充了listview，尽管我仍然不清楚CursorLoader。我试图显示单词含义的列表视图，但列表视图是如此不清楚（暗淡）。它看起来像一个模糊的背景。只有单击它时，列表项才会变得清晰。任何人都可以帮助我为什么这样以及如何解决？

＆＃39; wordmeanings.xml＆＃39;包含listview和＆＃39; wordmeaningrow.xml＆＃39;包含两个文本视图，分别用于单词和含义。

这是我的代码：

    public class WordMeaning_CursorLoader extends ListActivity implements LoaderCallbacks<Cursor>{

    // Identifies a particular loader being used in this component
    private static final int URL_LOADER = 0;
    Uri CONTENT_URI;
    SimpleCursorAdapter sAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.wordmeanings);

        String[] columns = {Constants.WORD_NAME, Constants.MEANING_NAME};
        int[] to = {R.id.tvword_wordmeaningrow, R.id.tvmeaning_wordmeaningrow};

        sAdapter = new SimpleCursorAdapter(getApplicationContext(), R.layout.wordmeaningrow, null, columns, to, 0);

        this.setListAdapter(sAdapter);
        // initializing the loader
        getLoaderManager().initLoader(URL_LOADER, null, this);
    }   // end onCreate

    @Override
    public Loader<Cursor> onCreateLoader(int loaderId, Bundle args) {
        switch(loaderId){
        case URL_LOADER:
            //returns new cursor loader
            String myUri = "content://com.test.provider.wordmeaning/tbl_word_meaning";
            CONTENT_URI = Uri.parse(myUri);
            return new CursorLoader(
                    WordMeaning_CursorLoader.this,
                    CONTENT_URI,
                    null,
                    null,
                    null,
                    null);

        default:
            return null;

        }   // end switch
    }   // end onCreateLoader

    @Override
    public void onLoadFinished(Loader<Cursor> arg0, Cursor cursor) {

        sAdapter.swapCursor(cursor);
    }   // end onLoadFinished

    @Override
    public void onLoaderReset(Loader<Cursor> cursorLoader) {
        sAdapter.swapCursor(null);
    }

}   // end WordMeaning_CursorLoader

wordmeanings.xml

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <ListView 
        android:id="@android:id/list" android:layout_width="wrap_content" android:layout_height="wrap_content"
        ></ListView>

</LinearLayout>

wordmeaningrow.xml

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" android:padding="10dp" >
    <TextView 
        android:id="@+id/tvword_wordmeaningrow" android:layout_width="fill_parent" android:layout_height="wrap_content"
        android:text="word" android:textAppearance="?android:attr/textAppearanceLarge" android:textStyle="bold"
        />
    <TextView 
        android:id="@+id/tvmeaning_wordmeaningrow" android:layout_width="fill_parent" android:layout_height="wrap_content"
        android:layout_marginLeft="10dp" android:text="meaning" android:textAppearance="?android:attr/textAppearanceMedium"
        />
</LinearLayout>

上面提到的昏暗的东西在8:30左右看起来像here。谢谢。我正在使用genymotion模拟器。

快照：

使用以下代码生成第三个快照：

public class WordMeaning_CursorAdapter extends ListActivity{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.wordmeanings);

        String myUri = "content://com.test.provider.wordmeaning/tbl_word_meaning";
        Uri CONTENT_URI = Uri.parse(myUri);
        //get ContentResolver instance
        ContentResolver crInstance = getContentResolver();
        Cursor c = crInstance.query(CONTENT_URI, null, null, null, null);
        startManagingCursor(c);

        // the desired columns to be bound
        String[] columns = new String[] {Constants.WORD_NAME, Constants.MEANING_NAME};

        // the xml defined views for each field to be bound to
        int[] to = new int[] {R.id.tvword_wordmeaningrow, R.id.tvmeaning_wordmeaningrow};

        // create adapter with cursor pointing to desired data
        SimpleCursorAdapter cAdapter = new SimpleCursorAdapter(this, R.layout.wordmeaningrow, c, columns, to, 0);

        // set this adapter as the list activity's adapter
        this.setListAdapter(cAdapter);
    }   // end onCreate

}   // end WordMeaning_CursorAdapter class