Do effectively immutable objects make sense?

Question

In the book Java Concurrency In Practice it explains the advantages of \"effectively immutable\" objects versus mutable objects concurrency-wise. But it does not explain what a

Answer 1

Yes, they make sense in some cases. An easy example is when you want some property to be generated lazily and cached so you can avoid the overhead of generating it if it's never accessed. String is an example of an effectively immutable class that does this (with its hashcode).