Hi kotlin peeps, I'm getting stuck on some java ko...

# announcements

[william]

Hi kotlin peeps, I'm getting stuck on some java kotlin interop. I have some android code (in java) that I am interacting with that simplifies to this:

public class FooService {
    public void addFoo(Foo foo) {
        // woop
    }

    public void removeFoo(Foo foo) {
        // womp
    }
}
interface Foo {
    void callback();
}

and then in the kotlin code I have:

class FooKotlin {
    fun buzz() {
        val fooService = FooService()
        fooService.addFoo {
            // do some callback stuff

            fooService.removeFoo(???)
        }
    }
}

I'm not sure what to replace the ??? with in order to remove the callback listener after it has executed once

[Zach Klippenstein (he/him) [MOD]]

you need to store your lambda in a val instead of passing it directly to addFoo.

[Zach Klippenstein (he/him) [MOD]]

probably something like

val fooCallback = Foo { … }
fooService.addFoo(fooCallback)

[william]

@Zach Klippenstein (he/him) [MOD] hey zach! i think i met you at a kotlin SF meetup once upon a time. but anyway i don't think that solves the problem of being able to remove it from within the lambda?

[Zach Klippenstein (he/him) [MOD]]

oh, sorry – you’d need to make a var and initialize it after declaring it

[william]

Can i do better than making it nullable?

fun buzz() {
        val fooService = FooService()
        
        var fooAction: Foo? = null
        fooAction = Foo {
            fooService.removeFoo(fooAction)
        }

        fooService.addFoo(fooAction)
    }

I suppose i could initialize it with an empty lambda but that also seems weird

[Zach Klippenstein (he/him) [MOD]]

i forget if you can use lateinit for local vars