I prefer that all of my Java classes provide for immutable objects unless there is a compelling need for them to be mutable. I’m not the only one who feels this way.

In Immutable Objects in Java, the four authors (Haack, Poll, Schafer, and Schubert) include a section on “enforcing immutability.” ...

Immutable objects are handy since they help with thread-safety and even just semantically since for many objects, if you modify it, it shouldn't be considered the same object.