利用rawQuery(String sql, String[] selectionArgs)查询表中的的数据

开始写的代码是这样子的：

private void findData(){ sqLiteDatabase=dbHelper.getWritableDatabase(); Cursor cursor = sqLiteDatabase.rawQuery("select id as _id,name from searchHisTab", null); Log.d("TAG","查找表中的数据"); Log.d(TAG,"cursor的数据为："+cursor.getCount()); cursor.moveToFirst(); do{ String id= cursor.getString(cursor.getColumnIndex("id")); Log.i("TAG","表searchHisTab的id="+id); String name = cursor.getString(cursor.getColumnIndex("name")); Log.i("TAG","表searchHisTab的name="+name); }while(cursor.moveToNext()); cursor.close(); sqLiteDatabase.close(); }

出现错误：

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.administrator.madioplayer2/com.example.administrator.madioplayer2.Search}: java.lang.IllegalStateException: Couldn't read row 0, col -1 from CursorWindow.  Make sure the Cursor is initialized correctly before accessing data from it.

原因：

在使用rawQuery(String sql, String[] selectionArgs)的时候，查询语句一定要有_id，也就是 Cursor cursor = sqLiteDatabase.rawQuery("select id as _id,name from searchHisTab", null); 还有这里的列要是_id,而不能是id String id= cursor.getString(cursor.getColumnIndex("id"));

修改：

private void findData(){ sqLiteDatabase=dbHelper.getWritableDatabase(); Cursor cursor = sqLiteDatabase.rawQuery("select id as _id,name from searchHisTab", null); Log.d("TAG","查找表中的数据"); Log.d(TAG,"cursor的数据为："+cursor.getCount()); cursor.moveToFirst(); do{ String id= cursor.getString(cursor.getColumnIndex("_id")); Log.i("TAG","表searchHisTab的id="+id); String name = cursor.getString(cursor.getColumnIndex("name")); Log.i("TAG","表searchHisTab的name="+name); }while(cursor.moveToNext()); cursor.close(); sqLiteDatabase.close(); }

运行就没有问题了