Advantage of Private constructor in C#

Question

what is the advantage of Private constructor in C# languages ?

Ehsan Sajjad · Answer

It is to restrict the creation of instance of that type from outside of it.it is useful when implementing singleton pattern.

Maha · Answer

Vulpes explanation is very excellent. Recently I came across a Chat Application program using delegates. That program demonstrates importance of his points.

Nick Chamberlain · Answer

Hi Shubham Vulpes mentioned a private constructor being used with the Singleton pattern. Recently I was in need of a Static Indexer and found that since C# doesn't allow this a Singleton can actually serve as a workaround. I wrote a short post about it here: http://buildplease.com/pages/singleton-indexer/ if you're interested in an example of a private constructor inside a Singleton class.

Sandeep Mishra · Answer

You can also create a constructor as private. When a class contains at least one private constructor then it is not possible to create an instance for the class. Private constructor is used to restrict the class from being instantiated when it contains every member as static .

S G · Answer

Hi shubham Private constructor... A private constructor is a special instance constructor. It is commonly used in classes that contain static members only. If a class has one or more private constructors and no public constructors then other classes (except nested classes) are not allowed to create instances of this class. Actually this is use for private constructor which r used to prevent new creation of the instances of a class when there are no instance fields or methods.

Jignesh Trivedi · Answer

hi Shubham A private constructor is a special instance constructor. It is commonly used in classes that contain static members only. If a class has one or more private constructors and no public constructors then other classes (except nested classes) are not allowed to create instances of this class. A private constructorhelp us to prevent the runtime from adding an empty contructure automatically Restricting access to object creation. hope this will help you.

Vulpes · Answer

A private constructor is useful when: 1. You want to control instantiation i.e. to limit the number of instances that can be created - say to one when implementing the 'singleton' pattern. 2. You want to avoid throwing an exception in the instance constructor itself if invalid arguments are passed to it. Even if you catch the exception the instance created may be left in an unstable state. In both these cases you can define a public static 'factory' method (or property) of the same class which only calls the private constructor when needed or safe to do so. You can also use a private constructor to prevent instantiation entirely but a better way to do this is to use a static class which can only contain static members and cannot therefore contain an instance constructor at all.