I have a method with this signature `fun translat...

# random

[juliocbcotta]

I have a method with this signature fun translate(key: String, body: (translation: String) -> Unit)
and I need to integrate it with Java files, which requires me to return Unit.INSTANCE;

like:

translate("MY_KEY", translate -> {
                // Do something
                return Unit.INSTANCE;
            });

Is it possible to avoid the return statement by changing the method signature or something ?

[ephemient]

use Callable<String> instead of (String) -> Unit

[ephemient]

or add an overload (and use JvmSynthetic or JvmName to hide the kotlin one from java and Deprecated(HIDDEN) to hide the java one from kotlin)

[juliocbcotta]

sorry but, it seems that Callable<String> is more like () -> String , not (String) -> Unit

[juliocbcotta]

I think I didn't understand the second comment...

[ephemient]

oh right, it's Consumer<String>

[Klitos Kyriacou]

By the way, there's no such thing as Unit.INSTANCE defined in Kotlin (as far as I know). Unit is defined as an object, i.e. there is a singleton class called Unit (corresponding to Java's void) and there is only one instance of that class, also called Unit. You don't need to return anything in a function declared as returning Unit, as your function will implicitly return the instance Unit.

[ephemient]

@JvmName("-translate") // hide from Java
fun translate(key: String, body: (String) -> Unit)
@Deprecated(message = "for Java only", level = DeprecationLevel.HIDDEN)
fun translate(key: String, body: Consumer<String>)

[ephemient]

Klitos, every Kotlin object (except for companions, those are a bit different) has a static Java field named INSTANCE, and it is required for Java interop in cases like this

[Klitos Kyriacou]

Thanks. Is the field INSTANCE only accessible from Java?

[ephemient]

yes

[ephemient]

https://developer.android.com/kotlin/interop#lambda_arguments