Is there a consise way to skip an assignment if a value is null? e.g.

// fun src.loadString(fieldName: String): String? {...}


dstBuilder.fieldA = src.loadString("aField") ?: throw Exeption("Field A is not present") 
// Instead of throwing, i want to leave dst.fieldA unset - skip this line and move to next.

Hello. What function can find the difference between collections of objects by ID? Example:

val list1 = listOf(ExampleObject(id = 1), ExampleObject(id = 2))
val list2 = listOf(ExampleObject(id = 2))

Result: listOf(ExampleObject(1))

Thanks in advance.

Looking for advice on this: I am ingesting a sequence of chars, I want to buffer them until I receive a particular xml end tag then flush the buffer. Is there a more efficient (while also easy) way to check for the existence of this tag at the end of the buffer? I think the trivial method is

endswith("</endtag>")

but this seems inefficient to run over the length of the buffer, especially if we get a char that can’t contribute to the terminal tag.

I have a question which is burning inside of my head recently... I've been doing a algorithm study with my friend. Till now we gather algorithm questions each other from internet and solve'em together every week. Gathering Q's every week is a bit painful and more hard to find them as the time goes by... what is a effective & efficient way to organize this gruop? any help?

What I'm looking for is what is the best way to organize the group... without gathering & picking tons of questions every week...

class OptionGroupControllerTest : KoinTest {

    private val optionGroup: String = this::class.java
            .getResource("/jsons/option_group.json")
            .readText()
            .replace("\n", "")
            .replace(" ", "")

    @BeforeTest
    fun setup() {
        startKoin {
            module {
                single<OptionGroupController>()
                single<OptionGroupService>()
            }
        }
    }

    @AfterTest
    fun teardown() {
        stopKoin()
    }



    @Test
    fun `create option`() = withTestApplication(Application::routes) {
        with(handleRequest(<http://HttpMethod.Post|HttpMethod.Post>, "/optionGroup") {
            addHeader(HttpHeaders.ContentType, ContentType.Application.Json.toString())
            setBody(optionGroup)
        }) {
            assertEquals(HttpStatusCode.Created, response.status())
        }
    }

}

My Routes:

fun Application.routes() {

    val controllerOptionGroup: OptionGroupController by inject()
    val controllerOption: OptionController by inject()

    routing {

        get("/") {
            call.respondText("OK")
        }

        get("/health") {
            call.respondText("OK")
        }

        route("/optionGroup") {
            post {
                try {
                    val message = call.receive<String>()
                    val messageOptionGroup: OptionGroupDTO = Mapper.read(message)
                    println("SERVER: Message from the client: $message")
                    call.respond(controllerOptionGroup.create(call, messageOptionGroup))
                } catch (ex: ItemException) {
                    call.respond(HttpStatusCode.BadRequest, mapOf("code" to ex.code, "messages" to arrayListOf(ex.message)))
                }
            }
        }
    }
}

And the exception is thrown at line:

call.respond(controllerOptionGroup.create(call, messageOptionGroup))

This problem only gives me when running the tests. When I run the application everything works correctly. I would really appreciate if someone can give me a hand with this 🙂

hello. please what would be the most elegant way to solve this. I have inputString representing datetime. I have list of DateTimeFormatters of supported formats. How would I parse it? each parsing attempt throws exception. at the end I would like to either throw exception or return default value if none of the formatters succeed. thx

Where do I get started with making a contribution to stdlib-common and making it available for ALL platforms?

Is it possible to get the instance of the companion object of an inheriting class?

Hey Kotlin folks - I’ve got a kotlin design challenge, looking for some ideas. I’m building a library that supports java & kotlin teams. The core is naturally Kotlin, but needs to be extensible by both Java & Kotlin. The only real hangup I’ve got is that some of the parts that need to be extended are part of the concurrency model, and I’m using coroutines to get that sweet sweet structured concurrency. Coroutines & java don’t seem to play very nice together. I’m not even talking suspend functions here, just trying to go between java & kotlin or vice versa, aside from the easy translation of completable futures. Anyway, the specific issue: I’ve got some behavior components that are plug able, and may need to do some async tasks. I provide them with a facade to interact with other parts of the system, which seems like a natural place to bridge between coroutines & traditional threading. However, I’m not seeing a way to go from a standard java threading model to coroutines. A coroutine wrapper for Runnable/Callable is trivial though. Thoughts?

Do you people know of any equivalent of ArchUnit for Kotlin? I couldn’t find one. The closest I found is this detekt plugin which checks a few design principles but it’s not the same thing.

Hi. The date for some kotlin articles is too old, March 1 1972 😂. Not sure if it is a site issue or Google indexing issue.

I'm running into a strange issue: lib A is a mixed kotlin+java project. I'm trying to use lib A from lib B, and all extension functions/free functions in lib A are unable to be found from kotlin in lib B. I am able to see them from java code in lib B. Is there something weird where the kotlin versions get clobbered?

Hi, is there a way to use static c library in kotlin mutliplatfom project?

anybody came across this?

# JRE version: Java(TM) SE Runtime Environment (8.0_261-b12) (build 1.8.0_261-b12)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (25.261-b12 mixed mode bsd-amd64 compressed oops)
# Problematic frame:
# J 29740 C2 kotlin.reflect.jvm.internal.impl.descriptors.runtime.structure.ReflectClassUtilKt.getDesc(Ljava/lang/Class;)Ljava/lang/String; (73 bytes) @ 0x000000011803a082 [0x0000000118039e20+0x262]

Hello, guys! I'm getting a compiler crash when I'm using the kotlinx.serialization. Can you help me please and tell how can I make kotlin compiler more verbose to find where is the issue and file a bug (or event maybe a pull request to kotlin)? This does not work:

kotlinOptions {
    verbose = true
}

Hello 👋  Is anyone here looking for a full-time position as a Mobile Engineering Manager? I am working with a fun and very successful social media/dating app, who are looking for Android Manager to act as a support partner to the Director of Mobile, essentially taking some pressure from the team and allowing the product teams ideas come to life and helping engineers to thrive in their roles.  They are a diverse team who value communication & feedback, so they are looking for someone likeminded to lead their Android function.   They are all about work-life balance, it’s full remote until April 1st at least, you will get every second Friday off and flexible working through the year.  The company is offering up to $200k as a base salary, plus a healthy bonus, equity, unlimited holidays and many more fantastic benefits. They are on a mission to create a digital world which will allow singles to connect, rather than just swipe right or left.  If you like the sound of this role, please get in touch 🙂

Hi guys! Does anyone know if there is a better way to do this so that I don't have to do explicitly casting?

fun <T : Any> getFoo(defaultValue: T): Foo<T> {

    return when (defaultValue) {
        is Long -> LongFoo(defaultValue) as Foo<T> //LongFoo extends Foo<Long>
        is Int -> IntFoo(defaultValue) as Foo<T> //IntFoo extends Foo<Int>
        is String -> StringFoo(defaultValue) as Foo<T> //StringFoo extends Foo<String>
        else -> NonPrimitiveFoo(defaultValue, defaultValue.javaClass)
    }
}

Is it terrible to connect to an external service in the constructor? i.e...

init {
        factory = ConnectionFactory().apply {
            setUri(config_uri)
            // Attempt recovery every 5 seconds
            isAutomaticRecoveryEnabled = true
        }
        rabbitConnection = factory.newConnection()

Hi, regards from Mexico

Is there any operator for Iterables that allows you to map with some mutable state, then push that state to the next iteration? Sort of like a reduce but only to map not to flatten. I suppose I could

fold

with a mutable list of

Pairs

.

Is there a recommended library for SQL generation in Kotlin, preferably with an example? I don’t necessarily want an ORM but just type safety and composability

If anyone uses JaCoCo in CI pipelines (especially Azure), how has your experience been?

Does kotlin have an elegant equivalent to

chunked

, where the partial window is at the start? eg with list

[1, 2, 3, 4, 5, 6, 7, 8]

,

chunked

gives

[[1, 2, 3], [4, 5, 6], [7, 8]]

, but I want

[[1, 2], [3, 4, 5], [6, 7, 8]]

. Or do I have to modulo myself and chunk when I know it's a multiple of my chunk window?

just curious—anyone have a use case for using

Nothing?

in your code anywhere?

Anyone used KSP over KAPT yet? Does it do multi pass? I have a some kapt annotations that get their types from other annotation processing and the kapt stub's don't compile (ironically the rest of the project does after all the annotation processors run).

I'm using a Kotlin specific library. Everything works in JVM mode but when running the app as native somewhy this check fails. https://github.com/sksamuel/hoplite/blob/master/hoplite-core/src/main/kotlin/com/sksamuel/hoplite/decoder/DecoderRegistry.kt#L44

Hey guys, Can I do something like this with when expresion?

val arrayNumber = arrayOf(0, 1, 2, 3)

if (arrayNumber.contains(0)) {
    //DO SOMETHING FOR CASE 0
}

if (arrayNumber.contains(1)) {
    //DO SOMETHING FOR CASE 1
}

if (arrayNumber.contains(2)) {
    //DO SOMETHING FOR CASE 2
}

if (arrayNumber.contains(3)) {
    //DO SOMETHING FOR CASE 3
}

Thanks in advance!

kapt $ annotation processing : How exactly do you make one that's incremental? All the docs say "it's supported now" but none of them mention now to make one.