Hey everyone, I am new and I have a question regarding Google's new OS fucschia, How do you see Kotlin stacking up then? Google will try to push its own stuff like dart flutter golang etc isn't it? I am confused of Kotlin will make sense to put lot of effort?

Please anyone know any resource to learn DS and algorithm with Kotlin

I’m trying to track down an unexpected inequality between two objects, and trying to figure it out by looking at the fields manually is a little tedious

I try to create a function to identify data types

fun <T> checkType(args: T): String {
    return when(args) {
        Int -> "Yes! it's Integer"
        String -> "Yes! it's String"
        Boolean -> "Yes! it's Boolean"
        Double -> "Yes! it's Double"
        listOf<Any>() -> "Yes! it's List"
        mapOf<Any, Any>() -> "Yes! it's Map"
        else -> "Can't identify"
    }
}

But, when I call this function like

checkType("I have 3 cats")

the output always display

"Can't identify"

. What's wrong with my logic? Thanks in advance

I'm currently porting a desktop application that uses

java.util.prefs.Preferences

to Kotlin. Does anyone know of a decent wrapper to

Preferences

or a Kotlin alternative? russhwolf/multiplatform-settings adds suspend/flow wrappers. I'm looking for an easy way to get/put lists, maps, and objects to preferences. Android has really polluted the Kotlin search space. 90% of the results are talking about SharedPreferences or DataStore.

Why does this code

(1..10).forEach {
            println(it)
            return@forEach
        }

print all of 10 numbers? what does even "return@forEach" mean here? It seems to work more like "continue", instead of "break"?

What is the use of invoke operator? Do the parentheses not conflict with any constructors? I couldn't find a lot of context and examples online. Thank you to whoever can explain :)

kt
val m: Map<String, Int> = mapOf("a" to 42, "b" to null).filterValues { it != null }

Any possibility to infer the not null type by the compiler? Workaround is a manual cast

Given a function with a default argument, is there a way to call it with its default argument? I want to write a wrapper function for it while preserving the default argument value. Basically this, but without the if

fun foo(arg1: Int, arg2: Int = 42){ ... }

fun wrapper(arg1: Int, arg2: Int? = null){
    if (arg2 == null)
        foo(arg1)
    else
        foo(arg1, arg2)
}

Is there a way to initialize a delegated property in the same line? For instance:

fun main() {
    val test by MyCustomDelegate() = 5 //doesn't work
    test = 5 //This is the current workaround
}

I don't want to change the implementation of MyCustomDelegate per se, I just want to call its setter in line. Is that currently possible?

Hi, I'm trying to get 49 tiles from the "letterBag" to put in a grid. I'm not sure what I'm doing wrong; there are two "y"s and I got three in my grid. Any ideas? Code in thread.

Kotlin Flow have pipe like rxjs sample? https://rxjs.dev/api/operators/sample

Hi all, Is it possible to use cold flow builder with Broadcast receiver. Currently I am doing my job with the help of hot flow MutableSharedFlow. But I do not want to use it*.* To see full code see in thread.

is there anything in the stdlib to take a BlockingQueue and for-loop over it in a blocking fashion? Like take() would do, blocking when the queue is empty?

Is there a nicer way to write

val lambda = if (myClickHandler == null) null else {
    myClickHandler::onClick
}

I wish this was possible:

myClickHandler?::onClick

When I’m using

gradle run

,

readlnOrNull

immediately returns null without reading any input. How to fix it?

Just tried making the

main

function

private

in a kotlin file and it is still executable. How does JVM access the function if it is

private

and make it executable?

Why is this not possible:

fun interface A {
    fun foo(b: Int = 42) // Single abstract member cannot declare default values
}

why is this valid

maybeNull() ?: return

but this isn't

maybeNull() ?: { return }

If I want to run a kotlin script file from my code, what's the recommended way to do it? I've seen various repos for kotlinc wrappers, but those require the end user to have kotlinc installed an on PATH, rather than embedding the compiler in some way

Hello! Do you all use mapstruct? It’s giving us issues when we try to move from kotlin 1.4 to kotlin 1.6 and I’m wondering if the community is simply not using mapstruct or if you are and we’re just doing something wrong. If you’re not using it, do you write the mappers by hand or use something else? Thank you!

what would be a nice way to implement a keyTypeMap. Something like

Map<KClass<out T>, SomeType<T>>

currently we are filtering from a list in multiple factories which is an O(factories * N) problem. Ideally I just want to request a class type from a map and get the correct implementation

Hey guys, is there a specific naming convention for class fields which has a number in their name ?

class Apartment ( val room1: String, val room2: String )

Hello, noob question here, under what conditions we need to use

MyFunction.invoke()

instead of

MyFunction()

?

runBlocking{
println("init")                                  
 launch{
delay(200)                                        
println("launch one")
}                                                 
println("mid")
    launch{                                           
     delay(100)
     println("launch two")                          
   }
   println("end")                                  
 }
init
mid
end                                                  
launch two
launch one


suspend fun cli(arg:String)=Runtime.getRuntime() .exec(arg).getInputStream().bufferedReader().readLines().forEach(::println)


runBlocking{
   println("init")
   launch{
   cli("du -hs")
   println("launch one")
   }

   println("mid")

   launch{
   cli("ls")
   println("launch two")
   }
   println("end")
 }

//optput
init
mid
end
11G     .
launch one 
AR 
UB
storage
launch two

In this code why in second runBlocking i am not getting output like mentioned below where du -hs takes more time compare to ls command. In first runBlocking launch one has 200 delay so first second launch runs but in second runBlocking it doesn't why? Sorry for noob question or queries but I am new to coroutines and trying to learn. init mid end AR UB storage launch two 11G launch one

I want to write a wrapper client for a third-party REST service in Kotlin, and I'm looking for examples. Can anyone recommend a popular Kotlin client library that's well written? (e.g. Twitter API)

Hey guys, I have a problem with jackson deserialization I have a model that has a field of an Enum type

data class Person (val gender: GenderEnum)

GenderEnum

enum class GenderEnum(val type: Sring) {
MALE("MALE")
FEMALE("FEMALE")
OTHER("OTHER")
}

and my api response is

"data": { gender: "male" }

Now, I am getting an error saying,

Cannot construct instance of the Person class, problem: Parameter specified as non-null is null: gender

anyone has the problem with jackson before ?

I see this question got not answers 😞 Is it now possible after 1.5 year?

I was looking to use the

String.replace

function to replace some text. Specifically there was a place where this shows:

"""
  """

And I’d just like to replace it with:

"""

I was looking to use a triple quote String as I really like how I don’t need to escape stuff in there because it confuses me, but then I end up in this situation where I can’t really match a “”" inside it as it closes the string 😅 Is my only solution here to not use triple quotes since I can’t escape a “”" in there probably right? With a “\”\“\”\n \“\”\“” string instead?

fun main{
    val scope = getScope()
    when(scope){
        // scope not smartcast and thus error
        is DeeperScope.Impl1, is DeeperScope.Impl2 -> scope.someVar = "2" 
    }
}

interface Scope
sealed interface DeeperScope : Scope{
    var someVar: String
    data class Impl1(override var someVar: String) : DeeperScope
    data class Impl2(override var someVar: String) : DeeperScope
}
fun getScope() : Scope = DeeperScope.Impl2("2")

Why can't scope be smartcast to DeeperScope in the when? Both implementations have their common parent as DeeperScope