Question

我有一个ListFragment，它通过加载器加载它的数据。到目前为止，我使用内置的R.layout.list_item和SimpleCursorAdapter。但是现在，我必须在每个列表项上做一些自定义格式化，并且需要使用自定义列表项布局，所以我必须将我的ListFragment转换为使用我的自定义Cursor Adapter。我不明白的是，如何绑定数据，这些数据是异步加载到我的列表视图中的。到目前为止，我的ListFragment和GewichtListViewAdapter。

这是我的listfragment：

public class GewichtListViewAdapter extends CursorAdapter {

public GewichtListViewAdapter(Context context, Cursor c, boolean autoRequery) {
    super(context, c, autoRequery);
}

@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
    return LayoutInflater.from(context).inflate(R.layout.listview_item_gewicht, parent, false);
}

@Override
public void bindView(View view, Context context, Cursor cursor) {

    // Find fields to populate in inflated template
    TextView gewichtTextView = (TextView)view.findViewById(R.id.gewichtTextView);
    TextView gemessenAmTextView = (TextView)view.findViewById(R.id.gemessenAmTextView);

    // Extract properties from cursor
    String body = cursor.getString(cursor.getColumnIndexOrThrow("body"));
    int priority = cursor.getInt(cursor.getColumnIndexOrThrow("priority"));

    // Populate fields with extracted properties
    long geburtsdatumLong = cursor.getLong(cursor.getColumnIndex(GewichtContract.Columns.GEMESSEN_AM));
    LocalDate geburtsDatumLocalDate = new LocalDate(geburtsdatumLong);
    DateTimeFormatter fmt = DateTimeFormat.mediumDate();
    String str = fmt.print(geburtsDatumLocalDate);
    gemessenAmTextView.setText(str);

    double gewichtDouble = cursor.getDouble(cursor.getColumnIndex(GewichtContract.Columns.GEWICHT));
    BigDecimal gewichtBigDecimal = new BigDecimal(gewichtDouble, MathContext.DECIMAL32);
    gewichtTextView.setText(String.format("%.1f", gewichtBigDecimal));

    }
}

这是带有Loader的ListFragment的摘录：

public class GewichtListFragment extends ListFragment implements
    LoaderManager.LoaderCallbacks<Cursor>{



@Override
public Loader<Cursor> onCreateLoader(int id, Bundle args) {

        String[] projection = { GewichtContract.Columns._ID, GewichtContract.Columns.GEMESSEN_AM, GewichtContract.Columns.GEWICHT };

        CursorLoader cursorLoader = new CursorLoader(getActivity(),
        GewichtContract.CONTENT_URI, projection, null, null, null);
        return cursorLoader;
        }

@Override
public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
        adapter.swapCursor(cursor);
        }

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




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

        if (getArguments() != null) {
        mParam1 = getArguments().getString(ARG_PARAM1);
        mParam2 = getArguments().getString(ARG_PARAM2);
        }

        // TODO: Change Adapter to display your content
        //setListAdapter(new ArrayAdapter<DummyContent.DummyItem>(getActivity(),
        //        android.R.layout.simple_list_item_1, android.R.id.text1, DummyContent.ITEMS));

        String[] uiBindFrom = { GewichtContract.Columns.GEWICHT, GewichtContract.Columns.GEMESSEN_AM };
        int[] uiBindTo = { R.id.gewichtTextView, R.id.gemessenAmTextView };

        getLoaderManager().initLoader(GEWICHT_LIST_LOADER, null, this);

        adapter = new SimpleCursorAdapter(
            getActivity(), R.layout.listview_item_gewicht, null, uiBindFrom, uiBindTo,
            CursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER);
        setListAdapter(adapter);
        }


}

如果使用简单游标适配器，它将附加在onCreate（）中。但是，我需要一个光标的引用，而我在onCreate（）中没有。此外，此时此日期（据我所知）尚未加载，所以我不知道如何绑定/附加此处。任何人都可以告诉我ListFragments，自定义光标适配器和加载器如何协同工作？

Answer 1

我的解决方案：

在onCreate（）中创建一个空的MatrixCursor并用它构造我的GewichtListViewAdapter：

        String[] columnNames = {GewichtContract.Columns._ID,
                GewichtContract.Columns.GEMESSEN_AM,
                GewichtContract.Columns.GEWICHT,
                GewichtContract.Columns.HUND_ID};
        MatrixCursor matrixCursor = new MatrixCursor(columnNames);
        gewichtListViewAdapter = new GewichtListViewAdapter(getActivity(), matrixCursor, true);
        setListAdapter(gewichtListViewAdapter);

在onCreateLoader（）中：

public Loader<Cursor> onCreateLoader(int id, Bundle args) {

        String[] projection = { GewichtContract.Columns._ID,
                GewichtContract.Columns.GEMESSEN_AM,
                GewichtContract.Columns.GEWICHT,
                GewichtContract.Columns.HUND_ID
                };

        CursorLoader cursorLoader = new CursorLoader(getActivity(),
        GewichtContract.CONTENT_URI, projection, null, null, GewichtContract.Columns.GEMESSEN_AM);
        return cursorLoader;
        }

ListFragments如何与Loader和自定义游标适配器一起使用？

1 个答案: