How to add kotlin source files to my java gradle groovy project? (NOT android)

Question

I have a build.gradle in groovy, for a Java project. I have kotlin sources somewhere else. How can I add those sources to my java project?

Answer 1

In build.gradle,

Change

plugins {
    id 'java'
    id 'maven-publish'
}

to

plugins {
    id 'java'
    id 'maven-publish'
    id "org.jetbrains.kotlin.jvm" version "1.6.20-RC2"
}

then add the kotlin sources also

sourceSets { 
    main.java.srcDirs += 'src/main/kotlin'
} 

Don't forget to respect the my/package/file.kt where file.kt has package my.package. So, the file must be in the folder path like this.

On java you can simply import like this:

import my.package.*;

If your kotlin compiles but you get import errors, then try to verify the folder where the kotlin file is, it's likely a problem with this path. I think the difference from Java is that the file does nothave to follow the name of the class.