Is `Unit` the equivalent of Java's `Void` rather t...

# getting-started

[Florian]

Is Unit the equivalent of Java's Void rather than lowercase void?

[spand]

It serves as both

[karelpeeters]

Kind of, Java Void doesn't have an instance but it allows null so that's kind of the single instance.

[Luca Nicoletti]

https://proandroiddev.com/kotlin-pearls-7-unit-nothing-any-and-null-cbbbbca86c2d

[Ruckus]

Technically, Void id equivalent to Kotlin's Nothing?

[Luca Nicoletti]

I think it’s the equivalent for kotlin’s Void?

[Luca Nicoletti]

a function which return Nothing can’t return, only throws or keep working

[Ruckus]

Kotlin doesn't have Void, that's from java. Nothing can't return, but Nothing? can return only null, just like Java's Void.

[Luca Nicoletti]

Sorry, meant Unit?

[Ruckus]

Unit? can return Unit or null

[Luca Nicoletti]

Unit is mapped to Void in Java

[Ruckus]

No, Unit is mapped to void (lowercase) for return type in Java, but stays as Unit in other circumstances, such as generics.

[Luca Nicoletti]

Yep, and what Unit? is mapped to?

[Ruckus]

It will stay Unit?

[Luca Nicoletti]

into Java code

[Ruckus]

Yes

[Luca Nicoletti]

there’s not Unit? in Java…..

[Ruckus]

Sorry, It would just be Unit, but with Java;s implied nullability.

[Luca Nicoletti]

Got it 🙂

[Luca Nicoletti]

Thanks

[Ruckus]

You can try it:

// Test.kt
fun test(): Unit? {
    return null
}

// Test.java
TestKt.test();  // returns kotlin.Unit

[Luca Nicoletti]

Thanks 🙂