ScheduleWorks.UI.AddOrEditLessonForm.chooseAlternativeClassroomsForm_OnReadyButtonClicked C# (CSharp) Method

        void chooseAlternativeClassroomsForm_OnReadyButtonClicked(object sender, EventArgs e)
        {
            mLesson.AlternativeClassrooms.Clear();
            foreach(var i in chooseAlternativeClassroomsForm.GetSelectedItems()){
                foreach (var room in mDBManager.Classrooms)
                {
                    if (int.Parse(i.ToString()) == room.ID)
                    {
                        mLesson.AlternativeClassrooms.Add(room);
                    }
                }
            }
        }