Compilation error in Eclipse in Kotlin + Java project, but project builds with Maven

Question

This happens in a Java and maven project in Eclipse with a kotlin nature.

In this part of the code:

    val faces = figure.getFaces()       
    for (polygon in faces) {
        //...

I get the error below in eclipse, where faces , in the second line above, is underlined in red:

Cannot access class 'Polygon'. Check your module classpath for missing or conflicting dependencies

The project is a mix of Java and Kotlin. The figure object is an instance of a Java class, while the faces are a set of type Polygon which is in a different project that is pure Kotlin (ie Polygon is a Kotlin type, in a separate Kotlin project).

This Kotlin project where Polygon is, is indeed in the classpath as a Maven dependency, and in fact used by the Java class of which figure is an instance.

I think the problem is in Eclipse, because I can build the project with maven successfully. It looks like either a bug in eclipse or a configuration issue.

I know it's strange to have a mix of Java and Kotlin. I simply started this project in Java and then decided to convert it to Kotlin gradually. So far I haven't had many issues but I'm aware that Kotlin tools and support in eclipse are not mature yet.

Answer 1

Not much of a proper solution: I converted my Figure class to Kotlin and the problem went away, but I can do that because I have full control on my project.

Possibly newer versions of the eclipse plugin won't generate this error or, as suggested in the comments, switching to IntelliJ IDEA is another option.