I’m used to making Android apps in Java but I wanted to try making an app in Kotlin. I created the Kotlin project, and I have a nice, Kotlin-app by now. However, when I wanted to create a new fragment, I realized that I have been using both Java Class files and Kotlin Class/File files in my project all this time. I was not aware of it. Yet, the project works properly and there are no Kotlin errors.

Is there a noticeable difference between using only Kotlin Class/File files in your Kotlin project VS using Java Class files in your Kotlin project?

I don’t see any difference. The code snippet suggestions are the same, there are no warnings or errors, the syntax highlighting works properly. Someone please explain! 🙂