How to make sure that there is just one instance of class in JVM?

Question

I am developing a design pattern, and I want to make sure that here is just one instance of a class in Java Virtual Machine, to funnel all requests for some resource through a s

Answer 1

Use enum. In Java enum is the only true way to create a singleton. Private constructors can be still called through reflection.

See this StackOverflow question for more details: Implementing Singleton with an Enum (in Java)

Discussion: http://javarevisited.blogspot.com/2012/07/why-enum-singleton-are-better-in-java.html