Can you explain singleton pattern?

 Posted by ArticlesMaint on 9/25/2009 | Category: Design Pattern & Practices Interview questions | Views: 6004

There are situations in a project where we want only one instance of the object to be created and shared between the clients. No client can create an instance of the object from outside. There is only one instance of the class which is shared across the clients. Below are the steps to make a singleton pattern:-

1) Define the constructor as private.
2) Define the instances and methods as static.

Below is a code snippet of a singleton in C#. We have defined the constructor as private, defined all the instance and methods using the static keyword as shown in the below code snippet figure ‘Singleton in action’. The static keyword ensures that you only one instance of the object is created and you can all the methods of the class with out creating the object. As we have made the constructor private, we need to call the class directly.

Figure: - Singleton in action

Note :- In JAVA to create singleton classes we use the STATIC keyword, so its same as in C#.

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