Whats the most idiomatic way to extend a primitive type in kotlin? For example in the context of an Android app, I want to build a type

Force

from

Double

which represents a force value converted to the appropriate unit (lbs/kg) based on user preferences. The type would encapsulate the conversion logic

Hello, everyone! 😊 Is there a reason to the following code give me a Java warning? I made it nullable because this is a non-required foreign key.

internal inline class CategoryId(val value: Long?)

fun test(){
    CategoryId(12)
}

Warning:

Use Long.valueOf(12) instead

message has been deleted

is there some elegant way in Kotlin to allow some syntax like the following one?

class Asdf private constructor() {
    companion object {
        operator fun invoke(s: Asdf.() -> Unit) {
            this.s() // doesn't make sense, Asdf().s() would work instead
        }
    }
}

// to be called as follows:
Asdf { }

this doesn't work because there's no

this

in a companion object. I guess I could have a lazy property to an

Asdf

instance, but can I have no instance at all?

Hey folks, this is fairly small and succint but was wondering if there was a "nicer"/more kotlinesque way of doing it?

val avatarList = mutableListOf<Int>(1,2,3)

fun generateRandomAvatar(): Int? {
	val pick = avatarList.randomOrNull()
	if (pick !== null) avatarList.remove(pick)
	return pick
}

I'm passing a function with optional parameters as a parameter to another function

fun addPlayer(
		name: String,
		avatar: Int? = generateRandomAvatar(),
		id: String = UUID.randomUUID().toString()
	) { dostuff }
...
fun PlayerList(players: List<Player>, addPlayer: (String, Int?, String) -> Unit) {
    addPlayer("Player #${players.size}")<----error here
}

But I'm not sure how to convey in the signature that they're optional, maybe this isn't possible?

hey everybody I have a

coroutine channel

in a

viewmodel

, how can I collect changes in multiple places? I tried code below:

#1
channel.consumeAsFlow {}

#2
channel.consumeAsFlow {}

#3
channel.consumeAsFlow {}

but only the first one will get triggered

This message was deleted.

I was defining a variables const and I have doubts about good practices and most scalable design. What's a recommended ways? My Samples: • Method 1: Create Global without Wrapper. cons: No context and need added in name of variable. • Method 2: Create in Singleton Object.

# Method 1: 
private const val API_PATH = "<http://localhost:8080>"
const val WELCOME_ENDPOINT = "$API_PATH/welcome"

# Method 2:
object EndPoints {
  private const val API_PATH = "<http://localhost:8080>"
  const val WELCOME = API_PATH + "/welcome"
}

I've come across the use of a sealed class in the Jetpack Compose Jetnews example code that I think has general applicability. I'm new to Kotlin and don't understand this construction of a generic class with 2 type parameters. I'd appreciate pointers to docs or articles that explain it. Thanks!

sealed class Result<out R> {

data class Success<out T>(val data: T) : Result<T>()

data class Error(val exception: Exception) : Result<Nothing>()

}

Hey, this may be a dumb question but when adding the Kotlin plugin, the std will be automatically added to

compileClasspath

abd

runtimeClasspath

, is it possible to disable this and have it only as

testImplementation

?

Does anybody know how to request a slack invitation recently? The signup page just says to contact an admin if you don't have a Jetbrains email address.

Hi! Let's say I have a sealed class WriteOperation, with some data classes as children and I want to convert them to corresponding WriteModel classes of mongodb or sql query templates for relational db. So my code for now looks like this:

sealed class WriteOperation {
  data class Insert(...some props): WriteOperation()
  data class Delete(...some props): WriteOperation()
  data class Replace... and so on
}
// And then in mongo-related package I do:
fun WriteOperation.toMongoModel(): WriteModel = when (this) {
  is WriteOperation.Insert -> InsertOneModel(...initialization)
  is WriteOperation.Delete -> DeleteOneOperation(...initialization)
  is WriteOperation.Replace -> ...
  ... and also around 12 other conditions
}
// Same thing happens with SQL:
fun WriteOperation.toSqlQuery(): SQLQuery = when (this) {
  ...long and painful list
}

Is there any way of replacing those long when expressions with some kind of inheritance, extension or composition without referencing Mongo or SQL implementation in sealed classes?

Is there a way to dump IR, possibly a online service or something? playground doesn't seem to have any options regarding...

I just noticed I have some builds that use the repo

<https://dl.bintray.com/kotlin/kotlin-eap>

for accessing preview versions of Kotlin. What repo can I use instead, to remove my reliance on anything bintray/jcenter-related?

I have a few jobs in a class that I would like to set to null can cancel, but obviously this doesn't work, I get a

val cannot be reassigned

error, i think because i don't want to assign the local value in the forEach closure, but the property of the parent class. How could I do something like this?

listOf<Job?>(
            uiJob,
            authJob,
            videoEventsJob,
            videoJob,
            countdownJob
        ).forEach {
            it?.cancel()
            it = null
        }

Jetpack Compose for Desktop: Milestone 3 Released The Compose for Desktop journey continues! Since the last milestone release of Compose for Desktop, we’ve done our best to bring you an even better experience when building desktop UIs in a modern and declarative style. Today we’re publishing Compose for Desktop Milestone 3, which introduces significant rendering and interoperability improvements, and makes it even […] The post <a href="https://blog.jetbrains.com/kotlin/2021/02/jetpack-compose-for-desktop-milestone-3-released/"...

got-stuck let's say I have this code:

val string = "<p></p>this<p></p>"
        
val arrs = listOf("<p data-id=\"1\"></p>", "<p data-id=\"2\"></p>")

var replacedString = ""

arrs.forEach {
    val pTag = "<p></p>"

    replacedString = string.replace(pTag, it)

}

println(replacedString)

It should show

<p data-id="1"></p>this<p data-id="2"></p>

, but it shows

<p data-id="2"></p>this<p data-id="2"></p>

instead

I have a file with a lot of functions witch all have the same name and only the amount of arguments and the return type changes, every time I start to type the name of the function outside of the file, Intelij freezes almost immediately. Changing the name of the functions to contain the amount of arguments does not change anything. Does anyone know what the issue is and how I can fix this.

Anyone know if theres any particular way to inject our own

Pattern

object to

Regex

although given its a static I don’t think it’d make much of a difference

Is there any way to be able to pass a condition based on a data class property as parameter? (thread)

how do I deal with this?

val string = "8% of 25 is the same as <img class=\"limit\">There are no heroes in a punk rock band <img class=\"limit\">"

        val arraySearch = arrayOf("<img class=\"limit\">", "<img class=\"limit\">")

        val arrayReplacement = arrayOf("<img class=\"another-limit\" data-id=\"1\">", "<img class=\"another-limit\" data-id=\"2\">")

        arraySearch.forEachIndexed { index, it ->
            string.replace(it, arrayReplacement[index])
        }
println(string)

the string doesn't get replaced. still showing

8% of 25 is the same as <img class="limit">There are no heroes in a punk rock band <img class="limit">

where it should have been

8% of 25 is the same as <img class="another-limit" data-id="1">There are no heroes in a punk rock band <img class="another-limit" data-id="2">

`companion object {
    val SORTING_COLUMNS = mapOf(X to "Y")
    val DEFAULT_SORTING_COLUMN: String = SORTING_COLUMNS[X]!!
}`

Anything I could do here to avoid reductant

!!

?

I have seen that it is not available compound assignment for bitwise operators in Kotlin. Do you know if it could be implemented in the future or why it might not be possible? Sample:

//Java
n >>= 1;
//Kotlin
n = n shr 1 // E.g. n shr= 1

fun myFunc(handler: Result<String> -> Unit) ....

hi all, would like to ask for some suggestion on which is a better approach, to use

include

or

recyclerView

? this is probably will be long, but i'll try to keep it simple. so i have a layout, where in that layout there is 3 sub-menu clickable tab. the 3 sub-menu tab has about 90% same UI, where it's difference only on the icon image and title text. because i'm originally will use

recyclerView

, i had create the sub-menu UI on different xml file. i was thinking to use

recyclerView

and set the

itemCount

to 3, and then set each item UI differences(icon & text) programatically. but in that moment, i got a thought what if i create the whole 3 sub-menu tab on that separate xml file and then called the sub-menu tab file on main layout by using

include

. because of this, i'm quite confused, on which is recommended to use for a better approach on making layout UI? thank you

Hi there! I'm trying to find if is possible in Kotlin to define a custom accessor for a class or data class that simply returns the non-nullable version of a class field (using a fallback value). Can't figure out how the syntax would be for the following:

data class MyDataClass(private val myProperty: BigDecimal?) {
            val myProperty: BigDecimal = myProperty 
                get() = field ?: BigDecimal.ZERO       // <-- I want to just expose the non-nullable version of the property
        }

👆 I've just tried the above as per what I could grasp from https://kotlinlang.org/docs/properties.html#getters-and-setters but can't make it work 😬 Is that possible to redefine a property accessor in such way? If it is, which syntax/construct should achieve it? Thx!

We started weekly Kotlin discussions in my company. This often involves playing around with some code. What tools are you guys using for this? Options I'm aware of are • screen sharing - does not allow for multiple people to edit • Intellj "code with me" - heavy (e.g. requires install) and seems to loose synchronized view once in a while • codebunk - interview tool, does not support latest Kotlin What I really would like would be a collaborative mode in "play.kotlinlang.org" but that does not seem to exist. Any other suggestions?