Is this underscore naming convention common in Kotlin?

I've never seen it. To me, the missing val/var is enough to deduce that they are single use.

I’ve never seen it. It’s quite common in languages that don’t offer enforced visibility constraints though, e.g. JavaScript, Python

thank you guys

There’s one use for backing properties: https://kotlinlang.org/docs/reference/coding-conventions.html#property-names

Hey Florian, you’ll see in the next chapter that we move away from that convention pretty quickly, with the exception of properties with custom getters/setters. At the time of writing, we thought the community was going to coalesce around the pattern that Roman linked to, but it hasn’t been universal.

thanks for the clarification

Thanks for reading 🙌