D8, R8 and enums - Kotlin Vocabulary 

It's [enumm] and not [anoom], ight?

It is pronounced enumeration.

@@Blafaselblubb e-num

Nope. Different languages, different pronounciations.

He didn't say it will break but to avoid breaking the code enums will generate an array which will cause overhead

In java enum can break (not enum itself, the switch statement) if you change the order of constants and recompile the file containing this enum. It can't break in Android tho, so that's why R8 gets rid of it.

@@jaloveast1k But what if we recompile both the file containing the enum and the file with the switch statement? I can't see any problems here

@@ulmaxy The problem is that the generated bytecode of that switch statment will not change the position of the elements in the array, so, in each case scenario you have, if you changed the enum class the array will be still pointing at the same positions but with different values. If you use R8, it will get rid of that array and just get the enums from each case

Don't get it either... recompiling both files (library + client) should fix the problem

Kotlin doesn't support switch. It uses "when".

Only when you push a release in production. R8 takes its sweet amount of time for optimizing, which will make development slow. Also if your code has a lot of legacy debt, it's better to avoid it until that debt is reduced, in my experience .

He didn't say it will break but to avoid breaking the code enums will generate an array which will cause overhead

Enum isn't the issue; it's the combination of enum and when that introduces the overhead

@@adityavikramrajawat My question was why did the Kotlin compiler has to create a class and an array to generate enums with when expression. As far as I understand, when expression seems like a shorthand to the switch statement. It even reminds me of the Haskell's case statement. Java does switch expressions since Java 13 (although it's a preview feature), so I wonder how they had the bytecode implemented.

@@maalevolent8052 I think my wording isn't right. What I don't get is why does Kotlin require a class and an array in the first place. There are two kinds of when expressions, one with a subject to check on, and other variant which has the subject inside the conditions itself. The first case, is like case statement in Haskell. The second case however, can be converted by the compiler into an if-else chain. I don't understand why the enum with when construct break if the class is not generated there.

@@SriHarshaChilakapati video was a bit misleading. Java also generates these additional mappings if you use enums in switch statement, but the naming was different. So basically R8 was optimizing Java mappings, but not Kotlin ones (which are, again, almost exactly the same but with different naming). Now R8 will also take care of Kotlin mappings.

You just need to add some rules (for example, not to obfuscate the class that causes classNotFoundException) to your Proguard file (proguard-rules.pro).

you´re not alone here. Turning on code minimization and obfuscation is a tricky thing. In short: To make the compiled app smaller and harder to decompile, R8 (i.e. ProGuard) is changing all your class names and method names to something shorter. So "YourClass.withThisMethod()" may become "a.b()". If there is a place in your app that for some reason still expects the class name to be "YourClass", but now it is called "a", then you get the ClassNotFoundException. That`s where ProGuard rules come into play. Start googling from there.

@@FlorianMeyer1983 Thank you for your explanation. And yes, i did get my way around by ignoring some of those classes in my proguard rules. However, its still seems messy to me because i double checked that the code 'i wrote' and it has no reason to be still called by the string matched class name. But, i think its prolly because some of the dependencies im using require that exact same class/method name. i think even some of the core dependencies coming from android require the same class/method names e.g: i think android navigation components, android databinding ? In these case, i find it often difficult to debug the scenario, wish there was some more help idk maybe from the IDE or some plugin. Or Am i missing something useful?

@@ashiqurrahman-nu7ik Tooling could be better for sure. When you are facing runtime exceptions, I would recommend to use the "analyse APK" function in Android Studio to be able to dig into the obfuscated classes. For compile errors I have nothing useful. Try and error, research and gut feeling tbh.

you need to exclude a few classes. The crash usually happens from an external library, Please check the documentation of the library which you have used and add an exception for the mentioned classes in Proguard rules file :)

OMG DOTA!!!!! (my day job is kotlin - night job Dota XD)

lol.... saving dota2 with memes. never thought I'll see it here.

When you are a beginner sometimes you have to go through many different websites and videos in order to learn it.

@@aitortilla5128 Agreed any Recommendations

For an amateur coder, this stuff doesn't really matter. He's just talking about a small, optional optimization you can run on your code to make your app run just a little bit faster. Really not worth worrying about things like this until you start making large, performance-intensive apps.

Still, small bits and pieces of this kind of information gets stored somewhere in the back of your head until one day you go: Hey! I remember someone mentioning this. It's happened som many times to me. Enjoy being an amateur, by the way. It is a fantastic state of exploring new stuff all the time. Like being a child again. The more you learn the more you realize there's so much you don't know and that can sometimes be frustrating.

@@barteksvaberg4403 I think we are all amateurs every day of our life as programmers haha, we can have years of experience, projects, and so on, but there are always new things that we don't know and we need to explore, I think the word amateur describes a really big part of us since we are amateurs at first when we know how to code, how to use a library, and then when we master it we are confident to keep investigating, and this is why programming is really fun, we are always learning new things and new challenges everyday, is really nice :)