为什么setSelection方法在onLoadFinished中不起作用？

Question

我想在onLoadFinished方法的ListFragment中设置选择，但Log.v（TAG，“onLoadFinished：Selected id - ＆gt;”+ getSelectedItemId（））; line return onLoadFinished：Selected id - ＆gt; -9223372036854775808？

有什么问题？

 public void onLoadFinished(Loader<LoaderResult> loader, LoaderResult data) {
    adapter.swapCursor(data.cursor);

    // The list should now be shown.
    if (isResumed()) {
        setListShown(true);
    } else {
        setListShownNoAnimation(true);
    }
    if (data.cursor.getCount() > 0) {
        setSelection(0);
        Log.v(TAG, " onLoadFinished: Selected id -> " + getSelectedItemId());
    }        
}

谢谢！