[nightpool]

How would you handle validating numeric input in a hot path then? All of the solutions proposed in #5 are incomplete or broken, and it stems from the fact that Java's language design over-uses exceptions for error handling in places where an optional value would be much safer and faster.

[ivan_gammel]

Normally in 100% cases, with parseInt/parseDouble etc. Getting NumberFormatException so frequently on a hot path that it impacts performance means, that you aren’t solving the parsing number problem, you are solving a guessing type problem, which is out of scope for standard library and requires custom parser.

[nightpool]

Okay, but this contradicts your original statement that "Java doesn't steer anyone to use these [footguns]". Every language has a way to parse integers, and most developers do not need a custom parser. Only in Java does that suddenly become a performance footgun.

[ivan_gammel]

It does not. If you need to parse a number, you use standard library and you will be fine. The described case with huge impact on hot path is the demonstration why using brains is important. The developer that will get into this mess is the one who will find the way to suffocate his code with performance bottlenecks in thousand other ways. It’s not a language or library problem.

[dionian]

Yes, parseInt et al work very fast for good inputs. What percentage of your inputs are invalid numbers and why ?

[ivan_gammel]

> What percentage of your inputs are invalid numbers and why ?

This is a wrong question to ask in this context. The right question to ask is when actually exceptional flow becomes a performance bottleneck. Because, obviously, in a desktop or even in a server app validating single user input even 99% of wrong inputs won’t cause any trouble. It may become a problem with bulk processing, but then, and I have to repeat myself here, it is no longer a number parsing problem, it’s a problem of not understanding what your input is.

[kerblang]

> Java's language design over-uses exceptions for error handling

No, library authors' design over-uses exceptions. Also refer to people using exceptions to generate 404 http responses in web systems - hey, there's an easy DDOS... This can include some of Java's standard libraries, although nothing springs to mind.

Exceptions are not meant for mainstream happy-path execution; they mean that something is broken. Countless times I have had to deal garbage-infested logs where one programmer is using exceptions for rudimentary validation and another is dumping the resulting stack traces left and right as if the world is coming to end.

It is a problem, but it's an abuse problem, not a standard usage problem.

[nightpool]

I agree with you that the root problem is that the library author's design over-uses exception. But when the library in question is the standard library and the operation is as basic as Integer.parseInt, then I think it's fair to criticize that as a language issue, because the standard library sets the standard for what is idiomatic + performant for a language.

[kerblang]

There is nothing wrong with Integer.parseInt(). It blows up if you give it invalid input. That's standard idiomatic behavior.

It might be helpful to have Integer.validateInt(String), but currently it's up to author to do that themselves.