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Published on May 13, 2017 by kudvenkat

Text version of the video
csharp-video-tutorials.blogspot.com/2017/05/singleton-design-pattern.html

Slides
csharp-video-tutorials.blogspot.com/2017/05/singleton-design-pattern_13.html

Design Patterns Tutorial

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All Dot Net and SQL Server Tutorials in Arabic
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In this tutorial we will discuss
1. What is Singleton Design Pattern
2. Singleton as Creational Pattern
3. Implementation Guidelines
4. How do we implement a Singleton class

This is continuation to Part 1 of Design Patterns Tutorial. So please watch Part 1 before proceeding.

Singleton Pattern belongs to Creational type pattern. As discussed in our previous video, Gang of four have defined five design patterns that belongs to creational design type category. Singleton is one among them and the rest are Factory, Abstract Factory, Builder and Prototype patterns. As the name implies, creational design type deals with object creation mechanisms. Basically, to simplify this, creational pattern explain us the creation of objects in a manner suitable to a given situation.

Singleton design pattern is used when we need to ensure that only one object of a particular class is Instantiated. That single instance created is responsible to coordinate actions across the application.

Advantages and Guidelines for Singleton implementation.

Concurrent access to the resource is well managed by singleton design pattern.

As part of the Implementation guidelines we need to ensure that only one instance of the class exists by declaring all constructors of the class to be private. Also, to control the singleton access we need to provide a static property that returns a single instance of the object.

Singleton Class Implementation Example

Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
// First version of Singleton demo
namespace SingletonDemo
{
class Program
{
static void Main(string[] args)
{
/*
* Assuming Singleton is created from employee class
* we refer to the GetInstance property from the Singleton class
*/
Singleton fromEmployee = Singleton.GetInstance;
fromEmployee.PrintDetails(“From Employee”);
/*
* Assuming Singleton is created from student class
* we refer to the GetInstance property from the Singleton class
*/
Singleton fromStudent = Singleton.GetInstance;
fromStudent.PrintDetails(“From Student”);

Console.ReadLine();
}
}
}

Singleton.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace SingletonDemo
{
/*
* Sealed ensures the class being inherited and
* object instantiation is restricted in the derived class
*/
public sealed class Singleton
{
private static int counter = 0;

/*
* Private property initilized with null
* ensures that only one instance of the object is created
* based on the null condition
*/
private static Singleton instance = null;

/*
* public property is used to return only one instance of the class
* leveraging on the private property
*/
public static Singleton GetInstance
{
get
{
if (instance == null)
instance = new Singleton();
return instance;
}
}
/*
* Private constructor ensures that object is not
* instantiated other than with in the class itself
*/
private Singleton()
{
counter++;
Console.WriteLine(“Counter Value ” + counter.ToString());
}
/*
* Public method which can be invoked through the singleton instance
*/
public void PrintDetails(string message)
{
Console.WriteLine(message);
}
}
}

Leave a Reply

62 Comments on "Singleton Design Pattern"

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Vaddiparthi Venkata Murali Krishna
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Vaddiparthi Venkata Murali Krishna
20 hours 37 minutes ago

it's very good and useful. could you please upload few more videos

MhRiderGaurav
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MhRiderGaurav
8 days 7 hours ago

this is not real kuduvenkat .

Bruno Miguel
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Bruno Miguel
9 days 5 hours ago

Nice series but please improve your audio really. Thank you

Avish MSD
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Avish MSD
6 days 11 hours ago

Hello Bruno Miguael, Thank you for your feedback. Will try my best to improve it in the upcoming sessions. Thanks again for your support.

Vijay Tyagi
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Vijay Tyagi
9 days 7 hours ago

Sir please continue this series…. waiting for long..

Avish MSD
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Avish MSD
8 days 11 hours ago

Sure. Thank you

madan Chakravarthy
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madan Chakravarthy
9 days 9 hours ago

Thanks a lot for Singleton..Excepting more Factory, Abstract factory,Builder,observer,Adapter,Bridge..etc.

Avish MSD
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Avish MSD
8 days 11 hours ago

Thank you Mr Madan. Really honored. We are trying our best to explain each and every bit of it and give a different perspective to the design patterns so that its really easy to understand.

Tofael Ahmed
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Tofael Ahmed
9 days 21 hours ago

GRATE, waiting for next one.

Avish MSD
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Avish MSD
8 days 11 hours ago

Thank you. We are trying our best to upload as many as we can.

waqar abbas
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waqar abbas
10 days 2 hours ago

i expected this series from kudvankat sir,..but you are also very good.Do your best as kudvankat sir done .because many people even every one is comparing your standard with kudvankat.i am sorry you are not good as kudvankat that i can understand.and choice examples like kudvankat do because his examples talk every thing like standard, concept, etc..keep it up …. Thank You…

Avish MSD
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Avish MSD
8 days 11 hours ago

Thank you Mr Waqar Abbas. Really honored with your inputs. Yes, Vekat is absolutely fantastic totally agree with you. We are trying our best to come up with many examples for each and every line and declaration of a patternso that its very easy for any one to understand the design pattern. We will try to do our best. Thanks again.

Dattatray Pidurkar -pitrya
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Dattatray Pidurkar -pitrya
10 days 6 hours ago

I liked this new series of tutorial. I do have a question though. How frequently you are going to put tutorial videos?

Avish MSD
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Avish MSD
8 days 11 hours ago

Thank you so much Mr Dattaray Pidurkar. We are trying our best to post them as many as we can.

Andres Gonzalez
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Andres Gonzalez
10 days 22 hours ago

Too private static Program Instance = null;public static Program ProgramSingleton => Instance ?? new Program();

Avish MSD
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Avish MSD
8 days 11 hours ago

Thank you Mr Andres Gonzalez. We will discuss this in one of the upcoming sessions.

Zbigniew Ćwiąkalski
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Zbigniew Ćwiąkalski
11 days 5 hours ago
Hi ! I have a question. Why not utilize static class instead of Singleton pattern ? Is it equal to Singleton pattern ? What are potential downsides of this solution ? public static class Singleton { private static int intInstanceCounter = 0; public static void Message(String message) { Console.WriteLine(message); } static Singleton() { intInstanceCounter++; Console.WriteLine("Singleton instance counter = " + intInstanceCounter); } }
waqar abbas
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waqar abbas
10 days 2 hours ago

yes i have a same Question..why he did not use static class…?

Ashish Agarwal
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Ashish Agarwal
10 days 20 hours ago

Hi Pls see the conversation on comment of "deepak deshmukh"'

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