singleton « enum « Java Data Type Q&A

1. What is the best approach for using an Enum as a singleton in Java?

Building on what has been written in SO question Best Singleton Implementation In Java and specifically talking about using enum to create a singleton, what are the differences/pros/cons between (constructor ...

2. Are there penalties for Enum Singletons?

Are there (performance) penalties* associated with the Enum Singleton Pattern in any way, as it seems to be used less than the classical singleton pattern or the inner holder class ...

3. Is the Single-Element Enum Type Singleton really a widely adopted good idea?

Item 3 of Josh Block's Effective Java (Enforce the Singleton Property With a Private Constructor or an Enumerator) mentions that "While this approach has yet to be widely adopted, a single-element ...

4. How do I implement logging in an enum singleton?

I'm using an enum singleton, but implementing logging is troublesome. This:

public enum Foo {

  private final Logger log = Logger.getLogger(Foo.class.getName());

The logger is instantiated in the way ...

5. Using enums to implement utility classes and singletons

Peter Lawrey writes about Two Uses of Enums that most people forget on his blog. First of all, I hadn't forgotten - I hadn't even realised :) These approaches are ...

6. The best singleton pattern since java 5

Since Java5 it is said that the best way to create a singleton is by a single-element enum type. (Which I think is awesome by the way.) Example:

public enum SuperSingleton implements Zooma{

7. The better Java singleton pattern nowadays?

You know, that since Java 5 is released the recommended way to write Singleton pattern in Java is using enum.

public enum Singleton {
But, what I don't like ...

8. Implementing Singleton in Java

Please note that I have gone through the below thread : Efficient way to implement singleton pattern in Java To summarize, there are important considerations while writing a singleton :

  1. Multiple threads access ...

9. singleton using enum

I read a lot on stackoverflow regarding the creation of singleton classes using enum. I must have missed something because i can't reach the INSTANCE anywhere. this is my code:

public class UserActivity {