Hello, World! I have a pattern that happens a lot in our codebase: enums with a String key, and we need to get the enum value from the key, or a special “unknown” value. So what we do currently is something like:

enum class MyEnum(val key: String) {
    FOO("foo"),
    BAR("bar"),
    UNKNOWN("unknown");

    companion object {
        fun getByKey(key: String?): MyEnum {
            return MyEnum.values().firstOrNull { it.key == key } ?: MyEnum.UNKNOWN
        }
    }
}

I’m looking for a way to not repeat this companion object for all our enums. Possibly a combination of an interface and a generic extension function? Any idea? 🙂 [sorry I already posted this before to an unrelated channel by mistake]

i changed the jdk from 12 to 11. trying to run

./gradlew build

i now always get this error

> Task :authmock:compileKotlin FAILED
e: No class roots are found in the JDK path: /usr/lib/jvm/java-12-openjdk-amd64

any idea what to do?

java.lang.Long.parseLong()

Why isn't this available in the Kotlin

Long

?

I ran into an issue sooner today when I serialized a data class that contained an enum, and the hashcode was always different

What made me think that

Enum.foo

would sometimes be differente from

Enum.foo

, and that's impossible?

is there a way other than going down with annotation and code generation?

Has anyone seen the "mock-maker-inline" feature suddenly stop working? Was able to mock final classes yesterday but then this morning it just... stopped. Using Mockito 2 (2.17.0) and IntelliJ.

Is there a relatively simple way to convert a channel to a sequence? At present using a broadcast channel to send events through two separate coroutines for processing. I'm trying:

sequence {
                    yield(channelSubscription.receive())
                }

but that errors out with:

Restricted suspending functions can only invoke member or extension suspending functions on their restricted coroutine scope

Is there a standard way to read kotlin dsl from a file and construct the objects from it. For Example I want to read a text file containing kotlinx.html code.

Might need to add kotlin-reflect for extensions?

should use threads, guys

test_kt.kt

if I know that this Enum extends also a specific interface, is there a way to express it in its type?

val values: Array<out Enum<*>> = Enum::class.java.enumConstants

Hi All, Could you say which version of Gradle is minimal required to build my Kotlin v.1.3.21 project?

Got a bug report on KotlinPoet regarding the following scenario:

enum class RenderPassCreate(override val value: Int) {
    companion object
}

This is the code we currently generate, and it will not compile, with the error being

Expecting ';' after the last enum entry or '}' to close enum class body

. The compiler expects the following:

enum class RenderPassCreate(override val value: Int) {
    ;
    companion object
}

which in my opinion looks ugly. I wonder if there’s a hard technical limitation behind this, and whether the compiler could handle this better? Tried searching YouTrack and it doesn’t look like it’s been filed

Kotlin has more constructs that are expressions than Java has (e.g.

if

,

when

,

try

expressions in Kotlin, but not in Java). What was the reason that the assignment operator

=

is not an expression?

What's the best I can get to an enum entry alias?

Is there a better way to write

list.filter { ... }.isNotEmpty()

? IDEA is telling me that the calls could be simplified, but I’m not seeing how

does this look like a bug? I think the the debugger has issues with automatic type inference because this only fails without the cast, even though the linter tells me i shouldn't need the cast. I noticed something similar at runtime in some other code i wrote where the type is erased, and failed when it shouldn't have

Are coroutines guaranteed to run to completion (i.e. can they be interrupted) on a given thread as long as they don't suspend (i.e. call a suspending function)?

is there a way to add an extension function to a java class?

class Whatever // Java
// kotlin
fun Whatever.String.extend() = 3
fun a(block: Whatever.()->Unit) {
   Whatever().block()
}
// in order to do somewhere in code
    a {
        "hello".extend()
    }

Hi, does someone know if we have a docker image so we can build ios applications with kotlin? Or an example of a

Dockerfile

?

I’m trying to compile a kotlin project with jdk11 but I’m receiving this error:

> Task :common:linkTestDebugExecutableNativeAndroidArm32 FAILED
/root/.konan/dependencies/clang-llvm-6.0.1-linux-x86-64/bin/llvm-lto: error while loading shared libraries: libtinfo.so.5: cannot open shared object file: No such file or directory
error: compilation failed: The /root/.konan/dependencies/clang-llvm-6.0.1-linux-x86-64/bin/llvm-lto command returned non-zero exit code: 127.

Does someone knows how to fix this? The library

libtinfo.so.5

is missing. It looks like this could be related with

ncurses

. Some people suggested to install this package

yum install ncurses-compat-libs

but I don’t know which package I should install when using debian.

Does anyone know why you're unable to use multiple varargs as parameters in a constructor in Kotlin and if there might be a possible workaround?

Doesn't

Module... modules

mean you can pass in a vararg in to the function call?

@snowe honestly, this issue baffles me then

@snowe nice!!! Thanks for help with the splat. This is what the result looks like with the TornadoFX workaround:

Hello ! Kotlin language is cool . And I like Kotlin language can be used in multiple platforms (Kotlin-JS, Kotlin/Native) and beautiful Kotlin Coroutines . But I am supposed to give the intro to Kotlin language , highlight kotlins feature every week . Any ideas how can I make more people engaging in Kotlin? Still many people I find people using Kotlin are Java converts and Android developer . But I want to highlight other Kotlin features and make students know use Kotlin language . Any guidance can I get ? Any help would be appreciated . Thank you

Any ideas for why this weird output is happening?

Lets say

Foo

is a

Stream<Whatever>

, I want to map and convert it to a Sequence, is there any difference at all between these?

foo
.asSequence()
.map { it.doStuff() }

or

foo
.map { it.doStuff() }
.asSequence()