What Is Singleton Design Pattern In C# With Example?

What is Singleton pattern in C#?

The singleton pattern is one of the best-known patterns in software engineering.

Essentially, a singleton is a class which only allows a single instance of itself to be created, and usually gives simple access to that instance.

There are various different ways of implementing the singleton pattern in C#..

What is singleton class and its implementation?

The Singleton’s purpose is to control object creation, limiting the number of objects to only one. Since there is only one Singleton instance, any instance fields of a Singleton will occur only once per class, just like static fields.

What is meant by Singleton?

1 : a card that is the only one of its suit originally dealt to a player. 2a : an individual member or thing distinct from others grouped with it. b : an offspring born singly singletons are more common than twins.

Why Singleton is not thread safe?

In the above code, the getInstance() method is not thread-safe. Multiple threads can access it at the same time. For the first few threads when the instance variable is not initialized, multiple threads can enter the if loop and create multiple instances. It will break our singleton implementation.

What is factory pattern in C#?

In Factory pattern, we create the object without exposing the creation logic. In this pattern, an interface is used for creating an object, but let subclass decide which class to instantiate. The creation of object is done when it is required. The Factory method allows a class later instantiation to subclasses.

How would you implement the Singleton design pattern in C#?

There are many ways to implement a Singleton Pattern in C#.No Thread Safe Singleton.Thread-Safety Singleton.Thread-Safety Singleton using Double-Check Locking.Thread-Safe Singleton without using locks and no lazy instantiation.Fully lazy instantiation.Using . NET 4’s Lazy type.

How do Singleton patterns work?

Singleton pattern restricts the instantiation of a class and ensures that only one instance of the class exists in the java virtual machine. The singleton class must provide a global access point to get the instance of the class. Singleton pattern is used for logging, drivers objects, caching and thread pool.

Why is Singleton bad?

By using singletons in your project, you start to create technical debt. Singletons tend to spread like a virus because it’s so easy to access them. It’s difficult to keep track of where they’re used and getting rid of a singleton can be a refactoring nightmare in large or complex projects.

What is the benefit of Singleton pattern?

Instance control: Singleton prevents other objects from instantiating their own copies of the Singleton object, ensuring that all objects access the single instance. Flexibility: Since the class controls the instantiation process, the class has the flexibility to change the instantiation process.

Why do we use Singleton pattern in C#?

Singleton pattern is one of the most important design patterns in a programming language. This type of design pattern comes under creational pattern, as it provides one of the best ways to create an object. This pattern ensures that a class has only one instance and provides a global point of access to it.

Where do we use Singleton design pattern?

It is used where only a single instance of a class is required to control the action throughout the execution. A singleton class shouldn’t have multiple instances in any case and at any cost. Singleton classes are used for logging, driver objects, caching and thread pool, database connections.

How do you implement a singleton?

The most popular approach is to implement a Singleton by creating a regular class and making sure it has:A private constructor.A static field containing its only instance.A static factory method for obtaining the instance.

Why is singleton class sealed?

The sealed keyword means that the class cannot be inherited from. … Marking the class sealed prevents someone from trivially working around your carefully-constructed singleton class because it keeps someone from inheriting from the class.

Is Singleton class thread safe?

Thread Safe Singleton: A thread safe singleton in created so that singleton property is maintained even in multithreaded environment. To make a singleton class thread-safe, getInstance() method is made synchronized so that multiple threads can’t access it simultaneously.

Why constructor is private in Singleton?

A singleton class is one which limits the number of objects creation to one. Using private constructor we can ensure that no more than one object can be created at a time. By providing a private constructor you prevent class instances from being created in any place other than this very class.

When should you use a singleton?

A singleton should be used when managing access to a resource which is shared by the entire application, and it would be destructive to potentially have multiple instances of the same class. Making sure that access to shared resources thread safe is one very good example of where this kind of pattern can be vital.

Where do we use Singleton pattern in C#?

Singleton design pattern is one of the GoF (Gang of Four) design patterns, falls under Creational pattern. It ensures at any given point of time only one instance of an object is alive and it does supports lazy initialization.

What problem does Singleton solve?

The Singleton pattern is probably the most famous and at the same time the most controversial pattern known to us. It must be also be the simplest pattern to learn and implement. Like any other pattern, Singleton exists to solve a common business problem that is ‘managing the state of a resource’.