I am using both Kotlin and java in my codebase. But I was wondering if there is a way I can reference a kotlin function from java? Here's my kotlin code : MyEvent.kt
open class MyEvent {
@Inject
lateinit var myService: MyService
@Inject
lateinit var app: MyApp
var name: String = ""
var options: MutableMap<String, String> = hashMapOf()
var metrics: MutableMap<String, Double> = hashMapOf()
init {
app.component.inject(this)
}
fun identify() {
myService.identify()
}
}
Now, in my base application class call "MyApplication", I want to call identify function. (I . know in kotlin we can do this via MyEvent().identify ) but was wondering how do we go about it in java? Any clue?
Thanks in advance!
It's the exact same thing in Java. Keep in mind they share the same underlying bytecode.
final MyEvent myEvent = new MyEvent();
myEvent.identify();
Look at the produced bytecode for the Kotlin MyEvent class (decompiled)
public class my/package/MyEvent {
...
public final identify()V
L0
LINENUMBER 14 L0
RETURN // Omitted myService.identify()
...
A companion object is translated to a static class property in Java.
For example, for this Kotlin code
open class MyEvent {
companion object {
fun test() = ""
}
...
}
This is the resulting bytecode
static <clinit>()V
NEW my/package/MyEvent$Companion
DUP
ACONST_NULL
INVOKESPECIAL my/package/MyEvent$Companion.<init> (Lkotlin/jvm/internal/DefaultConstructorMarker;)V
PUTSTATIC my/package/MyEvent.Companion : Lmy/package/MyEvent$Companion;
RETURN
MAXSTACK = 3
MAXLOCALS = 0
}
Which means, basically
public class MyEvent {
public static final Companion Companion = new Companion(...);
...
}
So, in Java you'd access it using
MyEvent.Companion.test();
For
open class MyEvent {
object Factory {
fun test() = ""
}
...
}
It would be, in Java
MyEvent.Factory.INSTANCE.test();
Ultimately Java doesn't have the concept of companion objects.
Instead, static properties and methods are used.