getColumnIndex（_ID）返回零，getlong（getColumnIndex（_ID））=正确的值

Question

因此，当我使用int location = cursor.getColumnIndex(_ID)时，它始终返回零，尽管long locationId = cursor.getlong(getColumnIndex(_ID)返回7.为什么我会得到不同的值？

    if (locationCursor.moveToFirst()) {
        //This is where the problem is happening
        locationId = locationCursor.getLong(locationCursor.getColumnIndex(WeatherContract.LocationEntry._ID));
        //=7
        int location = locationCursor.getColumnIndex(WeatherContract.LocationEntry._ID);
        // = 0

Answer 1

cursor.getColumnIndex(_ID)返回0，这是数据库表中_ID列的索引（位置）

cursor.getLong(cursor.getColumnIndex(_ID))返回7，这是存储在当前光标所在的数据库表的列_ID中的值。