static void Main(string[] args) { Console.WriteLine("***Observer Pattern Demo***\n"); IObserver myObserver1 = new ObserverType1("Roy"); IObserver myObserver2 = new ObserverType1("Kevin"); IObserver myObserver3 = new ObserverType2("Bose"); Subject subject = new Subject(); subject.Register(myObserver1); subject.Register(myObserver2); subject.Register(myObserver3); Console.WriteLine("Setting Flag = 5"); subject.Flag = 5; subject.Unregister(myObserver1); Console.WriteLine("\nSetting Flag = 50");; subject.Flag = 50; subject.Register(myObserver1); Console.WriteLine("\nSetting Flag = 100"); subject.Flag = 100; }