Should I use final for all the unchanged variables in Java?

Question

As far as I see, final is commonly used comparing to the same situations in C#. There is no final in C#, but sealed is not heavily used like this. So, can we say that; if the value will not be changed, or at least we are sure, then we should use final for all the situations e.g. variable definitions, parameters, ...?

private final Integer LIMIT = 10;
private final String NAME = "John";

or

default Optional<EmployeeDTO> findByUuid(final UUID uuid) {
  ...
}

And should we use capital letters for the final variable names as constant values?

Use it if you think it makes your code clearer or might prevent an error. You don't need to use it everywhere possible. That would be cumbersome. — khelwood, May 10 '21 at 20:56
Note in Java the `ALL_CAPS` convention is typically reserved for fields that are both `static` _and_ `final` (that includes enum constants). Fields that are just `final` use the standard `camelCase` convention. — Slaw, May 10 '21 at 20:58
@khelwood In this scene, I think it only helps to prevent from further value assign and there is no difference for performance, etc. Is that true? — , May 10 '21 at 20:59
In the example you gave, `LIMIT` and `NAME` are actual constants (there's no means to set them to anything else), so you ought to make then `static final`. As for other cases... it's preference. I personally like when they're final, but adding the modifier clutters the code, so I usually don't. — chrylis -cautiouslyoptimistic-, May 10 '21 at 21:00
And, what about the constant values in Java? Is the only difference `final static` to use constant values? **AND** should I use **capital** letters for `final` variables as `constant` values in Java? — , May 10 '21 at 21:00
`final` fields _do_ have significant performance advantages, particularly in multithreaded code, since they have guarantees that they will never change. `final` method parameters don't. _Do not_ use `SNAKE_CASE` for `final` fields; use `camelCase` like for variables. — chrylis -cautiouslyoptimistic-, May 10 '21 at 21:01
@Slaw Thanks Slaw, I have just seen your reply. Then I will use camelCase for final and CAPITAL for `static final` meaning `constant` in Java. Is that true? — , May 10 '21 at 21:02
I think *effectively final* variables have the same performance advantages. — khelwood, May 10 '21 at 21:10
@khelwood Sorry, do not understand what you mean. Do you explain a little bit further? Do you agree with **chrylis-cautiouslyoptimistic-** for performance wise? — , May 10 '21 at 21:15
"effectively final" means a local variable that the compiler can tell does not ever get changed, so it can treat it as final even if it isn't declared final. — khelwood, May 10 '21 at 21:31
Then, can we say that we **should** use `final` for global values, but there is no difference when using `final` for local values and method parameters? — , May 10 '21 at 22:19
@khelwood Thanks, but I am confused with all of comments. So, could you please that **Then, can we say that we should use final for global values, but there is no difference when using final for local values and method parameters?** — , May 11 '21 at 08:20

Should I use final for all the unchanged variables in Java?

0 Answers0