C# 兩行代碼實現 延遲加載的單例模式（線程安全）

關鍵代碼第4，5行。

很簡單的原理不解釋：readonly + Lazy(.Net 4.0 + 的新特性)

    public class LazySingleton
    {
        //Lazy singleton
        private LazySingleton() { Console.WriteLine("Constructing"); }
        private static readonly Lazy<LazySingleton> Linstance = new Lazy<LazySingleton>(() => { return new LazySingleton(); });

        //not lazy Singleton
        //public static readonly LazySingleton instance = new LazySingleton();

        public String Name { get; set; }
        public static LazySingleton Instance { get { return Linstance.Value; } }

        //For test
        public static bool IsValueCreated { get { return Linstance.IsValueCreated; } }
    }

    public class LazySingletonDemo
    {
        public static void Execute()
        {
            Task.Run(() => Foo1());
            //Thread.Sleep(1000);
            Task.Run(() => Foo1());
            Task.Run(() => Foo1());
          
        }

        public static void Foo1()
        {
            if (!LazySingleton.IsValueCreated)
                Console.WriteLine("LazySingleton is not initialized");

            LazySingleton.Instance.Name = "HK";

            Console.WriteLine(LazySingleton.Instance.Name);
        }
    }

測試結果：