How to access variant.outputFileName in Kotlin

Question

We\'ve been using a snippet like this one to rename the APK file generated by our Gradle build:

android.applicationVariants.all { variant ->
    variant.o         


        

Answer 1

Browsing through the source code of the Android Gradle plugin, I think I found the answer - here we go:

We are actually dealing with objects of type BaseVariantOutputImpl and this class does have both these methods:

public String getOutputFileName() {
    return apkData.getOutputFileName();
}

public void setOutputFileName(String outputFileName) {
    if (new File(outputFileName).isAbsolute()) {
        throw new GradleException("Absolute path are not supported when setting " +
                    "an output file name");
    }
    apkData.setOutputFileName(outputFileName);
}

Using this knowledge we can now:

import com.android.build.gradle.internal.api.BaseVariantOutputImpl

and then cast our target objects like so:

applicationVariants.all(object : Action {
    override fun execute(variant: ApplicationVariant) {
        println("variant: ${variant}")
        variant.outputs.all(object : Action {
            override fun execute(output: BaseVariantOutput) {

                val outputImpl = output as BaseVariantOutputImpl
                val fileName = output.outputFileName
                        .replace("-release", "-release-v${defaultConfig.versionName}-vc${defaultConfig.versionCode}-$gitHash")
                        .replace("-debug", "-debug-v${defaultConfig.versionName}-vc${defaultConfig.versionCode}-$gitHash")
                println("output file name: ${fileName}")
                outputImpl.outputFileName = fileName
            }
        })
    }
})

So, I guess: Yes, there is some Groovy magic at work, namely that Groovy's dynamic type system allows you to just access getOutputFileName and setOutputFileName (by way of the abbreviated outputImpl.outputFileName syntax, as in Kotlin) from your code, hoping they will be there at runtime, even if the compile time interfaces that you know about don't have them.