Coding efficiently using any latest library features

Question

I have a specific code block and I would like to use it more efficiently, shortly using any feautures coming later than Java 8. I do not know if there exists any, so maybe I will continue doing it like before if you do not have any suggestion. This is the code block which I would like to modify:

if(page != null) {
  coPage = companyService.findByCity(city, Integer.valueOf(page)-1);
}else {
  page="1";
  coPage = companyService.findByCity(city, 0);
}

I tried to do it using Optional but I have a problem with the variable "page" because I assign a value to local variable inside the lambda expression which compiler does not allow me to do so.

Optional is not designed to replace null checks. It's not. Stop trying to replace null checks by methods of Optional. That's not what it's for. — JB Nizet, Aug 03 '19 at 17:23
I would rewrite that code as `companyPage = companyService.findByCity(city, page == null ? 0 : (Integer.parseInt(page) - 1));` This uses features from Java 1.0. And they still exist in Java 12. — JB Nizet, Aug 03 '19 at 17:26
How about `if (page == null) page = "1"; coPage = companyService.findByCity(city, Integer.valueOf(page)-1);`. Also, use `parseInt` instead of `valueOf`. — Andy Turner, Aug 03 '19 at 19:11

score 0 · Answer 1 · answered Aug 07 '19 at 16:09

This is quite simple to do with Optional:

coPage = companyService.findByCity(city, Integer.METHOD(Optional.ofNullable(page).orElse("1"))-1);

where METHOD is one of parseInt and valueOf respectively.

However, it's generally better to use Optional in the following manner, as specified by Brian Goetz

[Optional is] a limited mechanism for library method return types where there [needs] to be a clear way to represent "no result", and using null for such [is] overwhelmingly likely to cause errors.

Coding efficiently using any latest library features

1 Answers1