浅尝DesignPattern_Singleton

 Singleton

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 UML:

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SAMPLE:

    class SingletonClient
    {
        static void Main(string[] args)
        {
            Singleton singleton = Singleton.getInstance();
            singleton.SaySomething();

            // Wait for user
             Console.ReadKey();
        }
    }

    #region Singleton

    public class Singleton 
    {
        private volatile static Singleton _uniqueInstance;
        private static readonly object _syncLock = new object();
 
        private Singleton() {}
 
        public static Singleton getInstance() 
        {
            if (_uniqueInstance == null) 
            {
                // Lock area where instance is created
                 lock(_syncLock)
                {
                    if (_uniqueInstance == null) 
                    {
                        _uniqueInstance = new Singleton();
                    }
                }
            }
            return _uniqueInstance;
        }

        public void SaySomething()
        {
            Console.WriteLine("I am double checked, therefore I am");
        }
    }