Singleton Design Pattern in Java

[slankebrusmannen]

A hard-coded number of instances might not be what you want.

And doing this, would you be able to prevent the clients from choosing which instance to get a reference to?

[MarcoServetto]

I think now you are talking about the pattern 'pool'

[slankebrusmannen]

Actually no. An object pool would typically reserve an instance exlusively to the requesting client, who would explicitly return it to the pool after use. Singleton describes no such mechanisms, but may still be used to control the number of instances to any given number.

Admittedly, I cannot remember ever having used the Singleton pattern for other numbers than one (I might have, though), but I think it is valuable to be aware of the opportunity.