private void updateDataGrid()
        {
            try
            {
                citizenList = new List <Citizen>();

                foreach (Citizen citizen in AddUser.ReadAll())
                {
                    citizenList.Add(citizen);
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine("Fehler beim Auslesen:" + ex.Message);
            }
            ReadAll();

            listAllCitizens.ItemsSource = citizenList;
        }
        static void CreateCitizen(int citizenID, string name, string firstName, string gender, DateTime birthday, int income, int building)
        {
            Citizen newCitizen = new Citizen();

            newCitizen.citizenID      = citizenID;
            newCitizen.name           = name;
            newCitizen.firstName      = firstName;
            newCitizen.gender         = gender;
            newCitizen.birthday       = birthday;
            newCitizen.incomePerMonth = income;
            newCitizen.fk_buildingID  = building;

            try
            {
                Console.WriteLine("Der neue Bewohner:" + AddUser.Create(newCitizen));
            }
            catch (Exception ex)
            {
                Console.WriteLine("Fehler beim Speichern:" + ex.Message);
                Warning warning = new Warning();
                warning.Show();
            }
        }