Hello. If you are starting to learn algorithms, use my repository with the simplest and most famous algorithms on Kotlin!!!! Algorithms on Kotlin

lets say you want to apply something to the result of a completable future in a coroutine, but only after the completable future finishes and you don't want to explicitly await it, how would you do it?

what am I doing wrong? I also cant compile the code. The function itself has no error

what's the idiomatic way to check if 3 or 4 or even more variables are all the same? something like a == b == c == d ... ?

Hey everyone 👋 I am trying to create a gson type adapter to process the object after it is de-serialized, following the pattern described here, https://github.com/google/gson/tree/master/extras/src/main/java/com/google/gson/interceptors However, not getting the right approach to convert that impl to Kotlin . Specifically, using generic type on an interface and apply the interface to an annotation class. Could someone provide any ideas or hint to get this approach right. This is what I have got so far, https://gist.github.com/sushant-droid/a3b673f513717b43550950cbcc1307cb

Is Kotlin for JS a good option for devs who have not worked with JS / web before? Or does it assume familiarity with JS and its ecosystem?

Is there a recommended way in Kotlin to validate a BigDecimal to confirm with e.g.

totalDigits(10) fractionDigits(3)

?

Playing around with

buildMap

but please can someone explain why this gives a compilation error (unless I uncomment the null):

fun main() {
    buildMap {
        if (true) {
            println("test")
            // null
        } else {
            put("foo", "bar")
        }
    }
}

https://pl.kotl.in/sohJmyPiJ

hey, posting this here because i cant find a pure kotlin questions channel, what is the difference between, in a class, having

Class {
    fun foo() { // normal method definition }
    val foo = { // same method implementation, but its a lambda }
}

Hi everyone, I'm getting started with KMM with cocoapods as outlined in the documentation on the website, but I keep running into this error:

'pod install' command failed with an exception:

Cannot run program "pod" (in directory "...../iosApp"): error=2, No such file or directory

I installed cocoapods using ruby2.7.5, and I am on M1 mac, following the troubleshooting guide here(youtrack.jetbrains). My "pod install" command also works in the folder, I am just not sure why this error keeps showing up.

just drawing a blank here: is the not a shortcut for

if (predicate(x)) f(x) else null

?

Not sure what the right channel would be to ask this, but is there a hack to get a map of the named params of a function to their value. For example:

fun xyz(param1,param2,param3...)

and get something like

{"param1":param1, "param2": param2 … }

its very laborious and redundant to do mapOf. Any workarounds?

Hey, is it possible to make an abstract enum ? Or a type that is equal to Enum<T> with added methods ?

I'm not sure when exactly I'd use a value class. Does it make sense for something like this: (see thread)?

Hey everyone 👋🏻 I'm new to the community and would love some recommendations on resources to learn Kotlin. Any of your favorite books, courses, video series etc would be greatly appreciated!

The new Kotlin scripting tutorial (https://kotlinlang.org/docs/custom-script-deps-tutorial.html#project-structure) contains this little gem, and I cannot tell if it's a bug or a pun.

fun JsonObject.get<reified T : Enum<T>>(key: T): JsonElement {
  return this.get(key.name)
}

Hi there, I'm trying to make a generic function that helps make my json parsing a little easier. I'm trying to make it so I can pass any enum, rather than having to make a specific copy of this method for each of the decoding enums I'm using. It seems I'm messing up the syntax for saying "key is a value of some enum type". This is the only way I'm using this (to get the name of the key item), so I don't actually care if it's reified if I don't need to do so to implement this function. Can anyone steer me towards how to write this correctly? Non generic version:

fun JsonObject.get(key: EntryTypeAADeserializer.CodingKeys): JsonElement {
  return this.get(key.name)
}

Hello everyone. I’m having a hard time with an extension function on an out projected type.

fun <Next, Root> KProperty0<Next>.set(value: Next) = Value<Next, Root>(this, value)

Because KProperty0 is out projected, I don’t get any type checking for the value parameter. If the property is a String, I can put an Int in the value because they both inherit from Any. Is there anything I can do to make the type checking more rigid on this function? Looking for a more invariant type checking.

hello, everyone I have a question about coroutine, in the demo from document, they launch 100,000 child coroutine, each of them delay 5 seconds, I understand delay is suspend function, and I read source code, it will use handler(android) to deal with time(5 seconds) but the question I got is, cpu only proceed the task in thread, once the delay function suspend, how does it wait for complete, in handler, queue, or just switch between threads? and what if i actually make 100,000 api request, does it perform as well?

//sampleStart
fun main() = runBlocking {
    repeat(100_000) { // launch a lot of coroutines
        launch {
            delay(5000L)
            print(".")
        }
    }
}

Hi, I have a simple question, why inline function is only useful when there is a lambda as last argument ? Why couldn't use inline functions at other places ?

Hi everyone, I've got a Kotlin project (not Android) that involves many variables with user-specific values (e.g. username, password, time-table) I would like this data to be moved out of the code, and into a modifiable file. The goal is to make it easy for non-coders to modify values and use the program. What are my best bets here? (JSON / YAML / etc). And what library should I be using? Here's a link to the project: https://github.com/adizcode/ProxyMate

Hello everybody. I am fighting internally with Roman's article about exceptions: https://elizarov.medium.com/kotlin-and-exceptions-8062f589d07. I am not convinced about main parts of the article and would like to know how you guys handle them in real-world applications. Especially what type of exceptions you declare in KDoc. Whether you go deep within your function call stack and try to be as exhaustive as possible about exceptions. And on the caller side, whether you simply have

try { } catch(e: Exception) { }

just to be sure you don't miss anything even if the bottom API change?Thanks.

Hello, I have a small question 🙂 Is there a reason why the

suspend

keyword is required for function executed inside coroutines ?

Is there an easy way to convert an Int to a ByteArray in Kotlin (Multiplatform so no JVM methods)

Hello I'm new to kotlin, I'm still learning and I was wondering if there is any kotlin online course with a «valuable» certification I can get, any idea ? PS : Kotlin for web (server)* not Android

class A(val value:Int = 0) fun test(){ with(A(9)){ with(A(8)){ println(this.value) //output 8 println(this@with.value) //output 8 // My question is how to access A's object with value 9 } } }

why doesn't L13 work ?

I'm getting a type error that I don't understand, and was hoping someone could help me with it.

import java.io.File

private fun Format(filename: String): Format? {
    // Never mind the implementation here.
}

fun readFiles(files: Sequence<File>): Map<Format, List<Reader>> =
    files
        .groupBy { getFormat(it.toString()) }
        .filterKeys { it != null }
        .mapValues { it.value.map { f -> f.reader() } }  // ERROR: Type mismatch: inferred type is Format? but Format was expected

Is there

OrderedSet

(not sorted) in Kotlin? Any alternatives?