Unable to Run Kotlin Application in Eclipse

I got same issues as you. I tried a lot of ways but not work (like uninstall plugin, then install plugin again, delete project and create new project...)

How to fix: I created a new workspace and setup the helloworld project again. I see that class file generated and I can run it normally.

Note that, we create new workspace and not project. What I notice is workspace contain .metadata folder that may have lot of information for Eclipse.

Try new Kotlin File instead of Kotlin Class:

For me it happened only once. I think this is some glitch from the Kotlin plugin, when you first create a Kotlin file and try run it. Try "new Kotlin class" paste the same content and see if it works. After that you should be able to run both files as it happened to me.