Question

I have some confusion with singleton class, below are my some points:

1. Can singleton class have static method?,if yes then how we call that methods?
2. what is main difference between Static class and Singleton Class?

I have created my singleton class as follows:

 public class Singleton
    {
        private static  Singleton _instance = null;
        private static object chekLock = new object();
        private Singleton()
        {}

        public static Singleton Instance
        {
            get
            {
                lock (chekLock)
                {
                    if (_instance == null)
                        _instance = new Singleton();
                    return _instance;
                }
            }
        }

        public static void StaticAddMethod()
        {
            Console.WriteLine("Add Method");
        }

        public void AddMethod()
        {
            Console.WriteLine("Add Method");
        }
    }

In Above class structure I have created two method one is Static and second is non static, When I am trying to access Static Method it gives me compile time error.

How can I use static method of singleton class?

Answer 1

How are you trying to access it? To access a static method you use the type name:

Singleton.StaticAddMethod();

vs

Singleton.Instance.AddMethod();

Note also that there are simpler ways of implementing singletons that acheive the same effect with less locking etc.

Re the difference between singleton and static; a singleton might implement an interface, allowing you to pass it into existing code. You can also (as indeed you are doing) defer construction of a singleton (yet still allow access to the static methods that don’t involve the singleton instance). But yes: there is a lot of crossover between static and singleton.