Error when trying to define Functional (SAM) interfaces

Question

In Kotlin, i'm trying to define an Interface with only one method. When trying to the following code:

  fun interface someInterFace
{
    fun someFunc()
}

I'm getting the following error message: "expecting function name or receiver type" Can someone explain me what i'm doing wrong? I'm using it exactly as it described in: Functional (SAM) interfaces

Answer 1

You need to change the languageVersion of kotlin to 1.4 or above that. For that, you do not have to change the version of ext.kotlin_version to 1.4+, but You need to write just a few lines in build.gradle file:

kotlinOptions {
    jvmTarget = '1.8'
    languageVersion = "1.4"
}

You can now sync the gradle and your code will work now.