Can I declare a class as
public static final?
I don't know - can you? What happened when you tried to do that?
Don't be afraid of breaking Java by actually TRYING things! That is the best way to learn.
And you need to make up your mind WHAT your question is.
The thread subject says you want to know how to create a singleton. But then your actual question is about creating a static final class.
Which is it?
Use singleton classes. You can do it with factory methods.
public class SingletonClass
private final SingletonClass instance=new SingletonClass();
public static SingletonClass getInstance()
Make the constructor private, so that no object can be created for the SingletonClass from outside. Create a static method that returns the instance of the class. This method is called as factory method.