How do you name unused variables? If even just having to make that choice annoys you (it's not just me, right?), read on for how #JavaNext will fix that and make pattern matching (how's that related?!) more maintainable in the process. 🧵

TL;DR: Unused variables suck. They're rare now, but will be more prevalent soon. JEP 443 proposes to replace them with _ for cleaner code and better pattern matching. "This 🧵 should've been 📰" ⇝ nipafx.dev/inside-java-ne… "This 🧵 should've been 📽️" ⇝ youtube.com/watch?v=nP1k41…

@nipafx __

@nipafx map.computeIfAbsent(key, ignoreMe -> new ArrayList<>());

@nipafx @ammbra1508 Is it ok to use this for Map.computeIfAbscent()? String name = ...; map.computeIfAbscent(name, _ -> new Person(name)); Or is better to do this? map.computeIfAbscent(name, name2 -> new Person(name2));

@nipafx I usually delete unused variables 🤔 who keeps them ans why?

@nipafx I use "_" and then cry it doesn't pass the syntax check, and then cry some more.

@nipafx I'm from the future and I use _

@nipafx @java "peepeepoopoo"

@nipafx What are unused variables?

@nipafx @JosePaumard _ 🤪

@nipafx In Google, naming these `unused*` makes them exempt from our unused-variable checker. This is a better approach than `@ SuppressWarnings` because if it does become used the user will rename it and won't have some cruft to remember to go back and clean out.

@nipafx Usually just _unused for generic case, _ignored for exceptions, _k/_key for computeIfAbsent. With ide configured to suppress warning names prefixed with underscore

@nipafx @java I'm used to _ in Scala. Happy to see that it could be the same in Java.

@nipafx Funny how Java is always 10 years behind C#

@nipafx Usually $ ``` locks.computeIfAbsent(key, $ -> new ReentrantLock()); ```

@nipafx @java Gone

@nipafx "_" is the best in this context.

@nipafx I name such variables "ignore".

@nipafx ignored

@nipafx @java normally. I don't us it today, but that doesn't mean I won't use it tomorrow.

@nipafx InjectMocks needs it