I m looking into migrating a Groovy codebase to Kotlin I was

Question

I m looking into migrating a Groovy codebase to Kotlin I was doing OK with having the Kotlin code depend on the Groovy code but after some thought I think the migration will be easier if the Groovy code depends on the Kotlin code I m struggling to get `compileGroovy` to see the Kotlin classes though Could anyone give me some pointers

Rob Elliot · Answer

For reference this was the `build groovy` config I used to get Kotlin depending on Groovy ``` tasks named compileGroovy Groovy only needs the declared dependencies and not longer the output of compileJava classpath = sourceSets main compileClasspath tasks named compileKotlin Kotlin also depends on the result of Groovy compilation which automatically makes it depend of compileGroovy classpath += files sourceSets main groovy classesDirectory tasks named compileTestGroovy Groovy only needs the declared dependencies and not longer the output of compileJava classpath = sourceSets test compileClasspath tasks named compileTestKotlin Kotlin also depends on the result of Groovy compilation which automatically makes it depend of compileGroovy classpath += files sourceSets test groovy classesDirectory ```

August Lilleaas · Answer

how do you access the Kotlin classes Just in case you weren t aware many classes only exception is kotlin files with a single class with the same name as the file will get a Kt suffix

Rob Elliot · Answer

The classes have the correct names The problem is that the Kotlin classes are not on the Groovy compile classpath

Rob Elliot · Answer

I presume I need something along the lines of ```tasks named compileGroovy classpath = sourceSets main compileClasspath sourceSets main kotlin classesDirectory ``` but `classesDirectory` is not a property of `sourceSets main kotlin`

Vampire · Answer

There is an example of how to change the lanugage dependency order in the manual

Vampire · Answer

Vampire · Answer

It is for changing the order between Groovy and Java but I guess for Groovy and Kotlin it should be largely the same

Vampire · Answer

Ah now I see your problem There is no source directory set named kotlin like for groovy

Rob Elliot · Answer

Insofar as I understand that page it would mean this ```tasks named compileKotlin classpath = sourceSets main compileClasspath tasks named compileGroovy classpath += files sourceSets main kotlin classesDirectory ``` but `sourceSets main kotlin classesDirectory` doesn t seem to exist

Rob Elliot · Answer

What you said

Vampire · Answer

Try it with ` java ` instead of ` kotlin ` Iirc that s the way to go

Rob Elliot · Answer

`compileGroovy` is still reporting `unable to resolve class XXX` for all my Kotlin classes A `build classes kotlin` directory exists with my compiled Kotlin classes so I guess `compileKotlin` does have its own independent output Or would it have added it to `sourceSets main java classesDirectory` I do find it hard to navigate the Gradle model to work out what to do in these circumstances Unfortunately googling anything involving the words gradle groovy and kotlin inevitably brings up reams of results about the gradle DSL

Rob Elliot · Answer

The following seems to work ```tasks named compileGroovy classpath += files tasks compileKotlin destinationDir ```

Rob Elliot · Answer

The task dependencies are already correct as Groovy depends on Java and Java depends on Kotlin

Rob Elliot · Answer

Oh no that only worked with Kotlin 1 6 1 7 doesn t have `tasks compileKotlin destinationDir`

Rob Elliot · Answer

OK so with Kotlin 1 7 amp gradle 7 5 1 this works ```tasks named compileGroovy classpath += files tasks compileKotlin destinationDirectory tasks named compileTestGroovy classpath += files tasks compileTestKotlin destinationDirectory ``` If this is wrong please let me know