单例模式

  class Program
    {
        private static Dictionary<string, Display> dict = new Dictionary<string, Display>();
        private readonly static string DEFAULT_KEY = "Catch";
        private readonly static int NUM_MAX = 3;
        private static int num = 1;
        static void Main()
        {



            Display d1 = Program.getInstance();
            Display d2 = Program.getInstance();
            Display d3 = Program.getInstance();
            Display d4 = Program.getInstance();
            Display d5 = Program.getInstance();
            Display d6 = Program.getInstance();

            Console.WriteLine("d1=" + d1.GetHashCode());
            Console.WriteLine("d2=" + d2.GetHashCode());
            Console.WriteLine("d3=" + d3.GetHashCode());
            Console.WriteLine("d4=" + d4.GetHashCode());
            Console.WriteLine("d5=" + d5.GetHashCode());
            Console.WriteLine("d6=" + d6.GetHashCode());

            Console.Read();

        }
        private static Display getInstance()
        {
            string key = DEFAULT_KEY + num;
            Display disp = null;
            if (!dict.ContainsKey(key))
            {
                disp = new Display();
                dict.Add(key, disp);
            }
            else
            {
                disp = dict[key];
            }
            num++;
            if (num > NUM_MAX)
                num = 1;
            return disp;
        }


    }

转载于:https://www.cnblogs.com/snow365/archive/2010/08/31/1813598.html