I can place kotlin code both in `src/kotlin` and `...

# android

[Philip Dukhov]

I can place kotlin code both in src/kotlin and src/java , what are the benefits in using src/kotlin? I guess it's easier to process, but I wan't being able to found any details.

[andylamax]

It just a sourceSet.

Place kotlin files under src/kotlin and java file in src/java . While this is not a must (as you have noticed), It just makes finding things easier.

There are not processing benefits in placing kotlin/java files in one directory over another

[arekolek]

if you have mixed codebase, I'd just stick with src/java, separating classes by language doesn't make any sense to me, but it does cause confusion from time to time

for example if you convert a class from java to kotlin you need to remember to move it to src/kotlin

so there are drawback and I never saw any benefits

if you have a kotlin only codebase, then I guess having src/kotlin is nicer, since src/java makes little sense if there's no java

[Vampire]

It's imho just cleaner to have them separated.
Each language has its own folder and for most languages by default you have to use the language specific folder.

Afair JetBrains thought it would be beneficial for incremental adoption if you can mix it in the java folder to easier migrate a Java codebase step-by-step and thus made it in their Kotlin plugin so that you can have them in both places.
Imho it is totally unclear if you have Kotlin files in a java folder.

Technically there should not be any difference which you choose, the Kotlin compile task just taskes all Kotlin files from both folders.

[arekolek]

I disagree completely, so I guess "cleaner" is just a matter of personal preference here

[Vampire]

Always 🙂

[Vampire]

Actually the Maven and Gradle inventors think so too as the former invented (or at least conventionalised) this syntax and the latter overtook it
and all languages that are supported built-in follow this separation principle by default.
It is just the Kotlin plugin where JetBrains decided to use a different default.

Well, that's as always not the full truth, as Groovy supports joint compilation where you can freely use the Java classes from Groovy and the Groovy classes from Java,
you can indeed also have Java classes in the Groovy folder.

But as always, those are only conventions and if you don't like them you are anytime free to change it to whatever you want.
If you prefer to have all sources and resources directly under src, that's also just a configuration option away.