android - 将 SimpleCursorTreeAdapter 用于 ExpandableList 会产生错误 "Failed to read row 0, column -1"。找不到错误

Question

我想从 SQLite 数据库获取数据并通过 SimpleCursorTreeAdapter 填充我的 ExpandableListView，但它在某些地方失败了。我真的找不到问题所在，甚至不知道异常发生在哪里......

我的扩展列表适配器:

private class MyExpandableListAdapter extends SimpleCursorTreeAdapter
    {       

        public MyExpandableListAdapter(Context context, Cursor cursor,
                int groupLayout, String[] groupFrom, int[] groupTo,
                int childLayout, String[] childFrom, int[] childTo) {
            super(context, cursor, groupLayout, groupFrom, groupTo, childLayout, childFrom,
                    childTo);
            // TODO Auto-generated constructor stub
        }

        @Override
        protected Cursor getChildrenCursor(Cursor groupCursor) {
            Log.d("Calling getChildrenCursor()","OK");
            Cursor childrenCursor = dbAdapter.getTrackedValuesByDate(groupCursor.getString(groupCursor.getColumnIndex(DbAdapter.KEY_VALUE_DATE)));
            Log.d("getChildrenCursor()", DatabaseUtils.dumpCursorToString(childrenCursor));
            startManagingCursor(childrenCursor);

            return childrenCursor;
        }       
    }

这是我设置 ListAdapter 的 Activity 中的相关部分:

private void fillData()
    {
        Cursor dateCursor = dbAdapter.getAllDates();
        startManagingCursor(dateCursor);
        Log.d("fillData()", DatabaseUtils.dumpCursorToString(dateCursor));
        MyExpandableListAdapter myAdapter = new MyExpandableListAdapter(this, 
        dateCursor, 
        R.layout.expandablelist_header_date, 
        new String[] {DbAdapter.KEY_VALUE_DATE},    
        new int[]{R.id.expandablelist_header_date},             
        R.layout.listview_tracked_values, 
        new String[] {DbAdapter.KEY_INDICATOR_NAME, DbAdapter.KEY_INDICATOR_UNIT, DbAdapter.KEY_VALUE_VALUE},
        new int[]{R.id.list_trackedvalue_indicatorname, R.id.list_trackedvalue_unit, R.id.list_trackedvalue_value });

        Log.d("fillData()", "Creation successful");     
        this.expandableList.setAdapter(myAdapter);
        Log.d("fillData()", "Adapter set");
    }

以下是我的 dbAdapter 使用的两个函数:

public Cursor getTrackedValuesByDate(String dateString)
    {
        Cursor cursor = this.db.rawQuery("select * from "+DB_INDICATORS_TABLE+" i,"+ DB_VALUES_TABLE+" v where i."
        + KEY_INDICATOR_ROWID+"=v."+KEY_VALUE_INDICATOR_ID+" and v."+KEY_VALUE_DATE+"='"+dateString+"'", null);

        if(cursor!=null)
            cursor.moveToFirst();

        Log.d("getTrackedValuesByDate()", DatabaseUtils.dumpCursorToString(cursor));
        return cursor;
    }

    public Cursor getAllDates()
    {
        Cursor c = this.db.rawQuery("Select distinct "+KEY_VALUE_DATE+" from "+DB_VALUES_TABLE, null);
        if(c!=null)
            c.moveToFirst();

        Log.d("getAllDates()", DatabaseUtils.dumpCursorToString(c));
        return c;
    }

最后是 LogCat 的输出:

09-07 12:05:06.912: D/fillData()(1317): >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@41219990
09-07 12:05:06.912: D/fillData()(1317): 0 {
09-07 12:05:06.912: D/fillData()(1317):    trackDate=07.09.2012
09-07 12:05:06.912: D/fillData()(1317): }
09-07 12:05:06.912: D/fillData()(1317): 1 {
09-07 12:05:06.912: D/fillData()(1317):    trackDate=08.08.2012
09-07 12:05:06.912: D/fillData()(1317): }
09-07 12:05:06.912: D/fillData()(1317): <<<<<
09-07 12:05:06.952: D/fillData()(1317): Creation successful
09-07 12:05:06.952: D/fillData()(1317): Adapter set
09-07 12:05:07.012: E/CursorWindow(1317): Failed to read row 0, column -1 from a CursorWindow which has 2 rows, 1 columns.
09-07 12:05:07.012: D/AndroidRuntime(1317): Shutting down VM
09-07 12:05:07.048: W/dalvikvm(1317): threadid=1: thread exiting with uncaught exception (group=0x40a13300)
09-07 12:05:07.145: E/AndroidRuntime(1317): FATAL EXCEPTION: main
09-07 12:05:07.145: E/AndroidRuntime(1317): java.lang.IllegalStateException: Couldn't read row 0, col -1 from CursorWindow.  Make sure the Cursor is initialized correctly before accessing data from it.
09-07 12:05:07.145: E/AndroidRuntime(1317):     at android.database.CursorWindow.nativeGetLong(Native Method)
09-07 12:05:07.145: E/AndroidRuntime(1317):     at android.database.CursorWindow.getLong(CursorWindow.java:507)
09-07 12:05:07.145: E/AndroidRuntime(1317):     at android.database.AbstractWindowedCursor.getLong(AbstractWindowedCursor.java:75)
09-07 12:05:07.145: E/AndroidRuntime(1317):     at android.widget.CursorTreeAdapter$MyCursorHelper.getId(CursorTreeAdapter.java:436)
09-07 12:05:07.145: E/AndroidRuntime(1317):     at android.widget.CursorTreeAdapter.getGroupId(CursorTreeAdapter.java:191)
09-07 12:05:07.145: E/AndroidRuntime(1317):     at android.widget.ExpandableListConnector.getItemId(ExpandableListConnector.java:422)
09-07 12:05:07.145: E/AndroidRuntime(1317):     at android.widget.AbsListView.obtainView(AbsListView.java:2288)
09-07 12:05:07.145: E/AndroidRuntime(1317):     at android.widget.ListView.measureHeightOfChildren(ListView.java:1244)
09-07 12:05:07.145: E/AndroidRuntime(1317):     at android.widget.ListView.onMeasure(ListView.java:1156)
09-07 12:05:07.145: E/AndroidRuntime(1317):     at android.view.View.measure(View.java:15172)
09-07 12:05:07.145: E/AndroidRuntime(1317):     at android.widget.RelativeLayout.measureChild(RelativeLayout.java:602)
09-07 12:05:07.145: E/AndroidRuntime(1317):     at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:415)
09-07 12:05:07.145: E/AndroidRuntime(1317):     at android.view.View.measure(View.java:15172)
09-07 12:05:07.145: E/AndroidRuntime(1317):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
09-07 12:05:07.145: E/AndroidRuntime(1317):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
09-07 12:05:07.145: E/AndroidRuntime(1317):     at android.view.View.measure(View.java:15172)

如你所见，我上次的debug.log是Adapter设置为ListView，但是随后是芬尼托...我什至没有收到覆盖函数 getChildrenCursor(Cursor groupCursor) 被调用的日志消息，所以错误发生我不知道在哪里...

帮帮我，我要疯了...

Answer 1

来自 CursorTreeAdapter 的文档，它是 SimpleCursorTreeAdapter 的间接父级，您可以看到:

The Cursors must include a column named "_id" or this class will not work.

您在查询中遗漏了什么。