The Singleton is a particularly simple pattern because it only has one class and two responsibilities.
Thus, its participant list looks like this:
Create the unique instance
Provide a reference or pointer to that instance
Most patterns have much larger participant lists.
Singleton is such a simple pattern that it really does not say much about collaborations. Its collaborations list looks like this:
Clients use the
getInstance() method to get a pointer or reference to the unique instance of the Singleton.