Question

How do I create a reference to a constant object?

final Myclass obj = new Myclass();

does not work, it says obj(the reference) should not be re-assigned but we can still change the object referred.

I want to ensure that the object itself does not change once constructed.

Answer 1

Just make it immutable (like String is). Or wrap it in another object which restricts access to mutators of the object in question (like Collections.unmodifiableList() and consorts do).