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我有一个通过数据库查询填充的ListViewin a 。ListFragment当它第一次填充列表时，它会很好地加载所有数据onCreate()。但是当我重新查询数据库，将返回值分配给assignmentsCursor并调用notifyDataSetChanged()时，它不会更新adapter.mCursor。如果我在 Eclipse 中进入调试模式，我可以看到它assignmentsCursor.mCount已经改变，但是当我查看时adapter.mCursor.mCount，它和以前一样。（是的，我在notifyDataSetChanged() 被调用后检查。）

我的代码的相关部分：

SimpleCursorAdapter adapter;
Cursor assignmentsCursor;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if (savedInstanceState != null) {
        course = savedInstanceState.getShort(Values.ASSIGNMENT_KEY_COURSE);
    }
    setRetainInstance(true);

    // Create and array to specify the fields we want
    String[] from = new String[] { Values.KEY_TITLE, Values.ASSIGNMENT_KEY_COURSE };

    // and an array of the fields we want to bind in the view
    int[] to = new int[] { R.id.assignment_list_title, R.id.assignment_list_course };

    // Need to give assignmentsCursor a value -- null will make it not work
    updateAdapter();

    adapter = new SimpleCursorAdapter(context, R.layout.assignment_list_item, assignmentsCursor, from, to);
    setListAdapter(adapter);
}

public void onResume() {
    super.onResume();
    updateAdapter();
    refresh();
}

/**
 * Updates the content in the adapter.
 */
public void updateAdapter() {
    SharedPreferences sharedPrefs = PreferenceManager.getDefaultSharedPreferences(context);
    boolean showingCompleted = sharedPrefs.getBoolean(Values.ASSIGNMENT_KEY_SHOWING_COMPLETED, false);

    if (course < 0) // Showing assignments from all courses
        if (showingCompleted)
            assignmentsCursor = DbUtils.fetchAllAssignments(context, Values.ASSIGNMENT_LIST_FETCH, null, true);
        else
            assignmentsCursor = DbUtils.fetchIncompleteAssignments(context, Values.ASSIGNMENT_LIST_FETCH, null, true);
    else // Showing assignments from specified course
        if (showingCompleted)
            assignmentsCursor = DbUtils.fetchAllAssignments(context, Values.ASSIGNMENT_LIST_FETCH, course, true);
        else
            assignmentsCursor = DbUtils.fetchIncompleteAssignments(context, Values.ASSIGNMENT_LIST_FETCH, course, true);

}

private void refresh() {
    updateAdapter();
    adapter.notifyDataSetChanged();
}

帮我！！;)

PS如果您需要更多详细信息/代码，请告诉我。我很肯定数据库正在正确查询。

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1 回答 1

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感谢 Deucalion，我确定我错误地认为适配器引用了 assignmentsCursor 变量，而不是为自己创建了 Cursor 的副本。我需要做的只是调用adapter.changeCursor(assignmentsCursor)以便它更新其本地副本。再次感谢杜卡利翁！

于 2012-03-29T07:19:48.580 回答