1     internal class SingletonOne 2     { 3         private static SingletonOne _singleton; 4         private SingletonOne() 5         { 6         } 7  8         public static SingletonOne Instance 9         {10             get11             {12                 if (_singleton == null)13                 {14                     Interlocked.CompareExchange(ref _singleton, new SingletonOne(), null);15                 }16 17                 return _singleton;18             }19         }20     }