what is the sense of final ArrayList?

Question

Which advantages/disadvantages we can get by making ArrayList (or other Collection) final? I still can add to ArrayList new elements, remove elements and update it. But what

Answer 1

Making the variable final makes sure you cannot re-assign that objest reference after it is assigned. As you mention you can still use that lists methods to make changes.

If you combine the final keyword with the use of Collections.unmodifiableList, you ge the behaviour you are probably trying to achieve, for instance:

final List fixedList = Collections.unmodifiableList(someList);

This has as result that the list pointed to by fixedList cannot be changed. Beware however that it can still be change through the someList reference (so make sure it is out of scope after this asignment.)