Why

kotlin.io.AccessDeniedException

isn’t a alias of

java.nio.AccessDeniedException

on JVM? Why creating such a new class that might confused the user that tries to catch this exception?

Why does removing "redundant initializer" as suggested by IntelliJ in this code: https://pl.kotl.in/7Kcy18ROA drastically increases the time required to run the program? The

time

variable has a redundant initializer which is commented. When you uncomment and use that redundant initializer, program runs a lot faster. Findings: when using redundant initializer: 20000100000 in 28ms --> which is quite fast. when removing redundant initalizer: 20000100000 in 103ms --> which is slow but is recommended by IntelliJ. IntelliJ hint aside what causes the Kotlin program to run "slower" when NOT using redundant initlializer?

When using

thread

, the result is expected but when using

launch

from Kotlin coroutine, the result is wrong and not expected. Code: https://pl.kotl.in/cBD4j9XWb In the code, as expected when using the

thread

code in the for loop, the result prints 15000 but when using

launch

for loop, the result prints 0 !? which is not expected. Why is this happening and why

launch

is giving wrong answer?

This message was deleted.

Hi, I’m from python and newbie to kotlin/java. I’m wondering how to assign different annotation to variable and call function with it.

var metadata = field.getAnnotation(AnnotationA::class.java) ?: field.getAnnotation(AnnotationB::class.java)
if (metadata != null) {
    someFunction(metadata) // which has two overrided functions with AnnotationA and AnnotationB
}

Compiler says “None of the following functions can be called with the arguments supplied.” and it says metadata is casted to ‘Annotation!’ How can I set metadata AnnotationA or AnnotationB, and use my overrided function according to the type?

Hello 👋🏽 , Apologies if this is a silly question, but would anyone be able to help me understand what this error

Cannot use 'T' as reified type parameter. Use a class instead.

means in this situation? I’m trying to generalise the

decodeFromString

and

encodeFromString

but I’m confused why it doesn’t let me do that.

@ExperimentalLettuceCoroutinesApi
abstract class RedisDAO<T>(
    private val keyPrefix: String,
    private val ttl: Long, private val redisClient: BbcRedisClient
) {

    open suspend fun getValueFromKey(key: String): T? {
        val extractedValue = redisClient.getValueFromKey(key)
        return extractedValue?.let { Json.decodeFromString<T>(it) }
    }

    open fun buildRedisKey(identifier: String): String {
        return "$keyPrefix$identifier"
    }

    open suspend fun saveWithTTL(key: String, value: T) {
        val encodedValue = Json.encodeToString<T>(value)
        redisClient.storeKeyWithTTL(key, encodedValue, ttl)
    }
}

Any ideas on why Micronaut ignores my test when I add the decorator

@MicronautTest

?

@MicronautTest( environments = [ "Test"])
class RequestHandlerTestLocal: DescribeSpec ({

    lateinit var applicationContext: ApplicationContext
    describe("Lambda Tests") {

        it("Creates correct Audit errors") {
//            println( "hello-world" + applicationContext.environment )
            //TODO
        }
    }
})

result is an ignored test.

Is there any way by which, having a

List<String>

like this:

val myList = listOf("paramA","paramB","paramC")

I can enforce an API like this?

fun myFunc (paramA: String, paramB: String, paramC: String)

basically a function, which has those strings as names for String arguments?

how can I pass a property to a companion object?

I want to get started with Kotlin for JS, and generally use VS Code for all my other development. It seems the docs are only concerned with InteliJ. Does it make sense to try to use VS Code or is kinda required to use InteliJ for a good experience?

Question about floor division and mod. My mental model is basically splitting the number line into chunks of a given size.

mod

tells you how far into a chunk you are, and

floorDiv

tells you which chunk you are in. Is getting the start of the given chunk as simple as

floorDiv * chunkSize

? Is it more complicated than that? Is my mental model fundamentally wrong?

How do I store instances of an

enum class

implementing an interface in a

TreeMap

such a way that I can set/get set them without throwing a

ClassCastException

? So far I have:

interface MyEnumInterface {}

enum class MyEnumClass: MyEnumInterface { ... }

var myTreeMap: TreeMap<MyEnumInterface, (() -> (Unit))> = TreeMap()

however when I call this method, passing an instance of `MyEnumClass`:

fun add(howToExecute: () -> (Unit), myEnum: MyEnumInterface) {
   myTreeMap[myEnum] = howToExecute // ClassCastException here
}

... I get a

ClassCastException

. Why does this happen? Why doesn’t it happen when the instance is passed to the add() method? What’s the most appropriate resolution please?

is there a list structure in Kotlin which keeps distinct values only?

e.g.  val list = listOf(3,9,1,6,7)

if I add a new 9, it would removes the old one:

list.add(9)
println(list) // listOf(3,1,6,7,9)

I would like to get a list of the values, ordered by the map key:

val a = mapOf(2 to "W", 3 to "V", 1 to "T")

desired result:

val list = listOf("T","W","V")

I was reading you can do that using

sortedMap

, but it doesn’t come out on the IDE.

Hello everyone, this is my first message, I'm planing to learn Kotlin as my first programming language.

Hello everyone. I was quite surprised that the following code doesn’t get compiled

val map = mutableMapOf("key1" to 1)
map["key1"] += 2

Why Is it not possible to use increment in such a way?

I'm starting off w/ Kotlin, and I was wondering for retrieving console input, is it preferable to use

readLine()

from the kotlin.io package or to use `Scanner(System.

in

)` from the java.io package? I think my personal preference is going the Java route because I feel that returning

String?

from

readLine()

is something I don't want to deal with. But maybe I'm not using Kotlin's null safety as much as I should be?

so I have a list of orders and then a list of cars, when I get the list of cars I would like to take from it all the cars whose

id

exists in the list of orders

What does

Stub!

means? In kotlin code, I tried to see the Declaration of Exception. In there, I found a

Stub!

string. What does it mean. Image:

Could someone please help me out with some gradle stuff? the issue I’m having is that apollo (graphql client) generates inline bytecode or somthing because I have an error that says :

Cannot inline bytecode built with JVM target 1.8 into bytecode that is being built with JVM target 1.6. Please specify proper '-jvm-target' option
Adding support for Java 8 language features could solve this issue.

The app is an kmm project. In both the shared build as the android build file is the compileOptions with javaversion 1.8 set but still getting the error I don’t know gradle that well and if I need to place this somewhere else let me know

Got this pop up in AS and it 404s. What am I doing wrong?

Hello everyone, I am android dev and I interested in android compose and android news for developers, what channels do you recommend me?

Sorry, I didn't mean to send that, but I keep getting that alert in the build and I don't know what is going on or why I'm getting it. Am I doing something wrong when setting up the project?

Okay, finally got a valid output. Looks like I'm running Gradle 6.8

Hi! Is there a good persistence library (preferably a Kotlin one) for working with postgres’s json columns?

Is there any reason to prefer

fun main(args: Array<String>)

over

fun main(vararg args: String)

?

how about

blockList.all { name.contains(it, true) }

?

Hi guys, given a mutableSet, I’d like to remove all the items from a collection, and then just get X items from it. For example

myMutableSet.removeAll(collection)
myMutableSet.take(x)

now I’d like not to use take since the set can contain millions of items and I’d like not to copy all in a new set..any suggestions? There is no constraints on the “which” X items to take..random is fine