Add Kotlin style guide

[michl-b]

I would love to see your code style for Kotlin as a configuration file for IntelliJ

[criswonder]

refresh it

[tqkhanh29]

It's rated more than 1 year but why not for Kotlin?

[jolly336]

How it goes on?

[underwindfall]

up it. any update ?

[lowasser]

Google primarily uses the already-available Android Kotlin style guide, with only a handful of changes -- mostly that we use a 2-space indent.

For formatting, we primarily use ktfmt, which has an IntelliJ plugin.