Using Kotlin singleton from Java

Annotate your function with @JvmStatic so a real static java function is generated when compiling.

You can use:

object OrderTitle {
    @JvmStatic
    fun generateMessage(context: Activity, otherParameter: AType? = null): AnotherType {
        // Do some things
   }
}

and then you can call it from Java:

OrderTitle.generateMessage(...)