What is a singleton?

A singleton is a design pattern used when only one instance of an object is created and shared; that is, it only allows one instance of itself to be created. Any attempt to create another instance simply returns a reference to the first one. Singleton classes are created by defining all class constructors as private. In addition, a private static member is created as the same type of the class, along with a public static member that returns an instance of the class. Here is a basic example:

public class SingletonExample {

 private static SingletonExample _Instance;

 private SingletonExample () { }

 public static SingletonExample GetInstance() {

  if (_Instance == null)  {

    _Instance = new SingletonExample ();

   }

   return _Instance;

  }

}