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Difference between Static class and Singleton instance in C#

In this article, we will discuss the difference between the Static Class and Singleton Instance in C#. But before discussing their differences, we must know about the Static Class and Singleton Instance in C# with their examples.

Introduction of Static class in C#

One essential building block for structuring code and encapsulating functionality that doesn't necessitate instantiation in C# is the "static class". It is effectively a class that currently assigned the static keyword to it, which prevents it from being created like other classes. As an alternative, it serves as an empty container for static members, such as fields, methods, properties, and nested types, which can be accessible simply through the class name by themselves and don't need an instance of the class. Developing utility classes with common functions or constants, with the value file manipulation or arithmetic operations, is made especially easy with this capability. Static classes function well in situations where individual object instances do not need to be created since they are considered stateless, meaning they are missing instance members as well as the capacity to hold state.

Difference between Static class and Singleton instance in C#

Furthermore, they offer notable acceleration gains because static members are synonymous with the class type and lack the need for object creation. Static classes usually reside inside namespaces for logical structure, making access easier with fully qualified names or with the incorporation of directives for streamlined usage. Static classes are useful, but they have constraints. They are unable to contain instance constructors, act as base classes, or inherit compared to other types other than Object. When everything is considered, C# static classes are a successful method to organize code, improve readability, and maximize efficiency throughout a variety of software development scenarios.


Let us take an example to illustrate the static class in C#:


Square of 5 is 25


In this example, we utilize the static keyword to construct a static class called MathHelper.
We construct a static method named Square inside the MathHelper class, which accepts a double parameter number and outputs its square.

After that, we call the MathHelper class's Square function within the Main method for computing the corresponding square of a supplied integer and present the result.

Only static members (methods, properties, and fields) are allowed to be included in static classes, including MathHelper, and these components will not be able to being generated using the new keyword. Rather, according to what the Main function shows, we may access their members directly by using the class name.

Introduction of Singleton instance in C#

A design approach known as the Singleton pattern in C# limits a class to a single instance for the duration of the program. This single object is globally accessible, given that it is part of the Singleton instance, which additionally provides centralized management of its instantiation and use. The Singleton design, which is typically implemented as a class containing a private constructor and a static method to retrieve an individual instance, has a number of benefits, such as centralized configuration management, resource conservation, and easier access to resources that are shared. It is used in several cases where maintaining a single instance guarantees consistency and effective use of resources, which includes logging, database connections, and caching methods. Singleton instances provide a number of benefits, although considering possible problems with thread safety, lazy initialization, and lifetime management, they should also be carefully considered.

As a result, it's critical to use the proper techniques while building a Singleton instance in C# to alleviate these worries and guarantee the pattern's viability throughout the application architecture.


Let us take an example to illustrate the singleton class in C#:


ExampleMethod called

Features of the Singleton Class:

Class of Singletons:

The purpose of the Singleton class is to make sure that there will be only one instance of it for the duration of the application.

Self-Building Contractor:

As the Singleton class lacks a public constructor, different classes cannot attempt to instantiate it. It stops other code from immediately generating instances of the class in question.

Instance Variable Static:

The single instance of the Singleton class is maintained in a private static variable called instance.

GetInstance Technique:

Utilize the public static GetInstance() function of the Singleton class to obtain the one instance of the class.

It uses lazy initialization, whereby generates an additional instance of the Singleton class if the instance variable is null and returns the current instance otherwise.

Main differences between Static Class and Singleton Class in C#

There are several main differences between Static and Singleton Class in C#. Some main Differences between Static and Singleton class are as follows:

Features Static class Singleton instance
Expression: It is impossible to instantiate a static class. It cannot be capable of having instance members and is implicitly sealed. The people who make up it have to be completely immobile. A class with a single instance of it that can be created and utilized via an individual method or attribute is known as a singleton instance.
Application: You utilize static classes when you have utility functions or methods which don't need to maintain any state. They are frequently used for constants, extension methods, and utility functions. You utilize singleton instances when you just require one instance of a class to maintain its state throughout the whole application. They frequently play a role in resource management, configuration settings, and global state preservation.
Adaptability: As they cannot be instantiated, derived from, or applied to implement interfaces, static classes are less flexible. These must only have static members within them. As singleton instances contain ordinary classes which might participate in inheritance hierarchies, perform interfaces, and inherit from other classes, they offer greater flexibility than different kinds of instances.
Thread Security: Although static classes lack instance members and states, they are considered by nature thread-safe. Particularly in a multi-threaded context, singleton instances would require extra synchronization techniques (such double-checked locking or using Lazy) to guarantee thread safety.
Starting Point: Static classes have members that are made enabled for use for the duration of the program when they are built during assembly loading. Depending on the implementation, singleton instances can either be eagerly initialized (made at program starting) or lazily initialized (generated when first requested).
Life Cycle Supervision: Static classes are unable to be expressly released or disposed of; instead, their lifespan is fixed and linked to the application domain. The lifespan of singleton objects may be explicitly controlled further. When resources are no longer required, they can release them so that they can put IDisposable into practice.
Memory Utilization: When the enclosing assembly loads, static classes load through memory and use it to access their static members. Singleton instances are formed in memory upon initial access to and utilization of up memory for their instance members.

To sum up, while both static classes and Singleton instances offer a means of encapsulating code, their functions and attributes differ, as do their instantiation, use, flexibility, thread safety, initialization, memory usage, and lifecycle management aspects.


In conclusion, there are important design and architectural ramifications for the basic differences between a Static class and a Singleton Class in C#. Although their contents are sealed and are incapable of being instantiated, static classes can be employed as containers storing constants, extension methods, or utility functions in situations where state preservation is not necessary. On the contrary, singleton instances are ordinary classes that make instantiation possible and guarantee that there is only one instance for the program's lifetime. They are favoured when it comes to resource management, global state maintenance, or implementing more complicated behaviour. Static instances provide more versatility, enabling inheritance, interface implementation, and explicit lifecycle management, whereas static classes, by default, provide minimalism and thread safety.

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