The second performs more operations (assuming stdlib everything) - see https://kotlinlang.org/docs/reference/sequences.html for why and for the stdlib alternative

Is there a good resource for understanding the usage differences between

List

and

Array

in Kotlin? Or

Array<Double>

and

DoubleArray

? Meaning when should you use one or the other, not what they literally are in terms of blocks of memory or the like.

hi like golang can we return multi values?

instead of modeling with data class or data structure.

why kotlin is not used in competitive programming?

Hi all! Was wondering if I could get some help on this? We are looking to hire a senior Kotlin engineer and was wondering what are the key technical capabilities that one should have? Thanks in advance! 🙂

Is it possible to mimic Enum's values() with sealed classes so we can use resulting list (all subclasses) to access companion object/static properties/methods. Using reflection is ugly, more so from consumer side when we only want to access static data of the subclasses. What would be Design pattern to search for (that is solution irrelevant of the language)

I have a weird scenario and I was wondering if Kotlin has any language features that would make the solution more straightforward? I have a poorly designed 3rd party Java API that we must use. That library has the exact same class, let’s call it

Headers

, in a dozen or more packages but they do not implement an interface and all extend Object. I’ve struggling to come up with a solution that keeps the code DRY.

Style question: When overriding a nullable val property with a null, do you prefer

override val myVal = null

or

override val myVal get() = null

saw this in Strings.kt for

String.trim()

and im just curious, why the cast to CharSequence?

/**
 * Returns a string having leading and trailing whitespace removed.
 */
@kotlin.internal.InlineOnly
public inline fun String.trim(): String = (this as CharSequence).trim().toString()

Why is this invalid? `

data class File(val state: String, val integrationId: Int, val archiveId: String, val sysTag: String, @field:JsonSerialize(using = ToStringSerializer.class) val _id: ObjectId = ObjectId())

Is there a way to have an abstract @JvmStatic function in an abstract class or interface?

I have an interface which I would like to be comparable by equals but I cannot override the equals method in the interface because is a method of Any. But I can implement the compareTo method. Is there a way to achieve the comparison for objects inheriting an interface?

I'm declaring a

Map<KClass<out SomeClass>, KSerialzier<out SomeClass>

is there a way to make sure both generic types refer to the same type analogous to java e.g. https://www.informit.com/articles/article.aspx?p=2861454&seqNum=8

https://twitter.com/kotlin/status/1237324890719608834 Working with large numbers? You can use an underscore as a thousands separator, and make it easier to spot how many digits a number actually has. #KotlinTips https://t.co/6tSMInWrvY Twitter

given that

val sClass: KClass = String::class

gives me the

KClass

for

String

, how do I get the

KClass

for

String?

? I tried

val nsClass: KClass = String?::class

but that doesn’t compile.

Jetpack Compose Question: I am trying to get a android.ui.material.button to look pressed. How is that done in compose?

Coroutines: Given an input, I want to launch two coroutines to find a solution for that input. I know how to launch these two in parallel, but how do I make the coroutine that finds the solution first return the earliest, so that the root suspending function doesn't have to wait on the other coroutine when the solution is already been found. So basically, instead of

awaitAll()

I need something like

awaitAllFirstFinished()

brand new, and have a question; we were going over something in class and I wasn't able to get an answer; Can someone please tell me what the difference is between the first two photos and the last two photos? They use the same methods of interpolation, but my instructor was trying to emphasize that the first two won't work because the interpolation is happening within the println statement... but the last images are proof that it does work inside the println statement; I am so confused.

Suppose a class has two funs:

fun myFun(vararg ps: MyParam1)

and

fun myFun(vararg ps: MyParam2)

and we have a call like

myFun(*emptyArray<MyParam1>())

then AndroidStudio will give the warning

Remove redundant spread operator

which is wrong because it is not redundant (and indeed

myFun()

will give a compilation error).

Any good article or book on domain driven design?

Anyone here that can answer this query? https://kotlinlang.slack.com/archives/C7L3JB43G/p1583842157042100

Is there a good distributed job scheduler for Kotlin (Coroutines)? Maybe even one that can use MongoDB for coordination (or where support can easily be added)? Best one I could find so far is written in Java, based on threads and also a little dated: https://github.com/michaelklishin/quartz-mongodb

How to run Kotlin compiler `in-process`with incremental compilation on?

ktlint lexiographic import order is meaningless feature.

how to use specific ktlint --experimental feature like indentation?

I have a parent class in java that calls an overrided get method in a child class during construction. The child class returns a null object from the get method because the parent class is initialized prior to the child class. Is there a good workaround for this? Example Code:

abstract class Parent {

    init {
        print("Parent Init: ")
        var str = getString()
        println("  $str")
    }
    constructor () {
        print("Parent Constructor:  ")
        var str = getString()
        println("  $str")
    }

    protected abstract fun getString () : String

}

class Child : Parent {

    var myString : String = "test"
    init {
        print("Child Init:  ")
        var str = getString()
        println("$str")
    }
    constructor () {
        print("Child Constructor:  ")
        var str = getString()
        println("$str")
    }

    override fun getString() : String {
        return myString
    }

}

var child : Child = Child()
println("Main: ${child.myString}")

Example output

Parent Init:   null
Parent Constructor:    null
Child Init:  test
Child Constructor:  test
Main: test

BLE Question: Which framework is the most stable? Android BLE - android.bluetooth Nordic Android-BLE-Library - https://github.com/NordicSemiconductor/Android-BLE-Library FastBLE - https://github.com/Jasonchenlijian/FastBle

Hey, does anybody know a cool std lib function or combination of functions that would achieve the following?

val x = listOf("a", "a", "b").function(listOf("a", "c"))

where

x == listOf("a", "b")

When using

listOf("a", "a", "b") - listOf("a", "c")

I get

x == list("b")

but I want to have one

a

in there. I know that I could do:

var a = listOf("a", "a", "b")
val b = listOf("a", "c")
b.forEach {
    a = a - it
}

But I don’t really like the

forEach

and

var

in that solution.

Is it possible to get an out-of-the-box Gradle setup with Intellij? I'm really struggling with this.