c# singleton

public class SingletonOnDemand {
	
	private SingletonOnDemand () {}
	private static class Singleton {
		private static final SingletonOnDemand instance = new SingletonOnDemand();
	}
	
	public static SingletonOnDemand getInstance () {
		System.out.println("create instance");
		return Singleton.instance;
	}
}

using System;

namespace DesignPattern.Singleton
{  
  class Program
  {
    var printer1 = Printer.GetInstance();
	var printer2 = Printer.GetInstance();

    Console.WriteLine(printer1.GetHashCode()); //output 20538874
    Console.WriteLine(printer2.GetHashCode()); //output 20538874
    //both printer1 and printer2 has the same hash code
    //that is the same instance
  }  
  
  public class Printer
  {
      private static Printer instance;

      private Printer(){}

      public static Printer GetInstance()
      {
          if (instance == null)
          {
              instance = new Printer();
          }
          return instance;
      }  
  }
}