Hi! Is it possible to define an extension function in java code? https://stackoverflow.com/questions/56987823/define-kotlin-extension-function-in-java-code

Define that function as

protected

in the body of the Java class :

public abstract class BaseJava {
    protected void foo(String str, int bar) {
        // Implementation of your function.
        // Notice the signature : its first parameter is a String, which is the expected receiver of your extension function in Kotlin.
    }
}

In Kotlin, you could define this extension in each derived class :

class Derived : BaseJava() {
    private fun String.foo(bar: Int): Unit = foo(this, bar)

    fun myFun() {
        "Hello World!".foo(42)
    }
}

But that sounds like a lot of efforts just to have a nicer syntax for some function calls. I'd stick with calling the

protected

method by passing the

String

parameter.