Design Pattern - Singleton Pattern

In this post, I will explain how to create or implement singleton design pattern using c#. This pattern provides best way to create an object. This singleton class provides object which can be available without instantiate the object of the class.

Development :

1) Create a Singleton Class

	public sealed class Singleton
	{
	public static int counter = 0;
	// Threadsafety
	private static readonly object obj = new object();
	private static Singleton instance = null;
	// public property is used to return only one instance of the class leveraginmg on the private property.
	public static Singleton GetInstance
	{
	get
	{
	if (instance == null) // Double chcked null as lock is very expensive to use
	{
	lock (obj)
	{
	if (instance == null)
	instance = new Singleton();
	}
	}
	return instance;
	}
	}
	// private constructor used to prevent the class to instantiate multiple times.
	private Singleton()
	{
	counter++;
	Console.WriteLine("Number of Instanace created : " + counter.ToString());
	}
	public void PrintDetails(string message)
	{
	Console.WriteLine("Messsage from the Method :{0}", message);
	}
	}

view raw Singleton.cs hosted with ❤ by GitHub

2) Get the Singleton Object

	public class Program
	{
	static void Main(string[] args)
	{
	//Singleton Demo
	Parallel.Invoke(
	() => sc1(),
	() => sc2()
	);
	Console.ReadLine();
	}
	private static void sc1()
	{
	Singleton sc1 = Singleton.GetInstance;
	sc1.PrintDetails("Invoked First Method");
	}
	private static void sc2()
	{
	Singleton sc2 = Singleton.GetInstance;
	sc2.PrintDetails("Invoked Second Method");
	}
	}

view raw Program.cs hosted with ❤ by GitHub

3) Check the output ( Number of Instance should be 1 )

If you have any questions, post here. Also, provide your valuable suggestions and thoughts in form of comments in the section below.

Thank you !!!