I'm completely new to Kotlin and I need to rewrite a cross platform app to be native. I've already finished the Swift UI side and loved the declarative UI style. I saw Kotlin had entered beta with Jetpack Compose with their version of declarative UI. I understand it's in beta but how fluid is it it to use? I need to use Google maps and also braintrees drop in payment UI. SwiftUI had was to make representable views from UIKit incase you got in a corner with something that wasn't supported. Does Compose have something like that? I know for a fact there's no braintree support for Kotlin Compose but can you mix a Java view, wrap it in Kotlin and then add it to a compose view? I'm just trying to feel out if there's work arounds incase I would get stuck where there's no support

Could anyone help me out with reading from the InputStream? Whenever I receive the data and put it into a buffer, the elements in it seems to be inconsistent. For example I am expecting a buffer of [0,0,0,0,0,0,4,3,0]. sometimes I get the right values sometimes I get [0,0,0,0,0,0,3,0,0], or [0,0,0,0,0,0,0,3,4] or some different variation. I am not entirely sure if there is not enough time to update the buffer properly before it is being evaluated or if there is some other problem. This is being done within a

run()

function of a thread Its like the app is receiving the data from the inputstream consistently. It always varies Seems to be a problem when the number of bytes > ~6 for some reason?

Just wanted to see if anyone knows of an idiomatic way of adding a

,

between strings in a string builder. I know

joinToString

exists and it works great for arrays, but I basically want the same functionality for a string builder. Here's what I'm currently doing (no commas yet):

topic.data.forEach {
                    myBuilder.append("${it.city} ${it.status}")
                }
            }

Maybe I'm missing something basic. Thanks

how to make a function with one input parameter which returns the same type but retains nullability in a generic way? e.g.

T -> T

and

T? -> T?

how to call a java function called

to

from Kotlin? it keeps trying to use the

Pair

extension 🤔

Hello, I have a question regarding generics. I would like to store lambdas into a Map. And those lambdas have a generic parameter. So, I did this simple code

typealias AFunction<R, A> = suspend (args: A) -> Result<R>

val functionMap = mutableMapOf<String, AFunction<Any?, Any?>>()

fun <R, A> addFunctionToMap(name: String, function: AFunction<R, A>) {
    functionMap[name] = function
}

For some reasons, it doesn’t compile (on the line

functionMap[name] = function

) as it is saying it was expecting a type

AFunction<Any?, Any?>

and not

AFunction<R, A>

. I tried modifying a bit the

addFunctionToMap

function like this:

fun <R: Any?, A: Any?> addFunctionToMap(name: String, function: AFunction<R, A>) {
    functionMap[name] = function
}

But, it doesn’t change the compiler error. Do you have an idea how I could solve that? 🙏

When building an abstract class where you want the subclasses to provide some property, how would you decide between constructor arg versus abstract val?

Has anybody successfully managed to run linters with type resolution as triggers on their projects? Either CI after build or as pre-commit/pre-push git hooks?

Hi guys I'm participating on the AndroidDevChallenge and I do not know why my code is failing on UI test remotely

// generated by JsonToKotlinClass
data class JsonToKotlinClass(
    val `data`: List<Data?>?
) {
    data class Data(
        val id: Int?
    )
}

// generated by RoboPOJOGenerator
data class RoboPOJOGenerator(
    val data: List<DataItem?>? = null
)

data class DataItem(
    val id: Int? = null
)

fun main() {
    val jsonToKotlinClassData: JsonToKotlinClass.Data = JsonToKotlinClass.Data(1)
    val roboPOJOGeneratorData: DataItem = DataItem(1)
}

The former is generated by JsonToKotlinClass plugin and latter is generated by RoboPOJOGenerator. Which one would you prefer? Besides differences in syntax and how they are used are there other pros and cons of these two approaches.

I'm dealing with function overloading when the parameters are lambdas and stumbled upon the following case:

fun foo(block: String.(String) -> Unit) {

}

fun foo(block: () -> Unit) {

}

fun main() {
    foo { it: String ->
        // calls foo(block: String.(String) -> Unit)
    }
    
    foo { // ERROR
        // how to call foo(block: () -> Unit)
    }
}

Basically is there a way to specify in the second case that I want to call

foo(block: () -> Unit)

. When I specified the type of the lambda argument, it seemed that the compiler was able to figure it out, however

it: Unit

doesn't work for the second case.

Where to start as a java developer: Kotlin for Java Developers | Coursera Kotlin for Java developers | Android Developers I would recommend having something like this pinned in the getting-started, it’s not the first time I see this sort of question coming around :)

I am having a hard time understanding lambda expressions in Kotlin...

I feel like I found conflicting info on how to add a code snippet to a kdoc for my function. @yole in an old SO post said to just use triple backticks

But kdoc documentation currently links out to <https://daringfireball.net/projects/markdown/syntax#precode> which seems to say that you should just indent?

Which one is correct?

I just want to have something like this

```/**
* Sample usage
* ```kotlin
* blah.boop()
*

*/``` Is that correct? I thought I would maybe get some syntax highlight in the IDE, but nothing. Is having the kotlin keyword following the backticks not needed?

Is there a more concise way of doing the following:

fun main() {
    println(alternatingCase("hello kotlin"))
}

fun alternatingCase(param: String) : String {
    val array: CharArray = param.toCharArray()
    var newString = ""
    for ((index, char) in array.withIndex()) {
        newString += if (index % 2 != 0) char.toUpperCase() else char.toLowerCase()
    }
    return newString
}

Hello all, is there a way to do one of the two following things? 1. in a normal blocking function, determine if the function was called from a coroutine context 2. Warn a user in a meaningful way that they should not call a specific blocking function from a coroutine context (ideally by failing to compile as if i tried to call a suspend fun from a blocking fun, but a really good warning is good enough for me) I know that if I add a false

@Throws(IOException::class)

to my method, it gets highlighted as an inappropriate blocking call in IDEA, and I can just add docs to the method and hope people read them when they get the unrelated warning. However, I’m hoping for something a little more direct. Anyone have any ideas or pointers?

Any1 know how one can code with Kotlin on a chromebook

how come this doesn't smartcast the result of first to a String?

val l = listOf<Any>("foo")
l.first { it is String}.length // unresolved reference: length

And is there a way to get this to work with a smartcast?

package leetcode

import kotlin.collections.set

fun main() {
    val nums1 = intArrayOf(1, 2, 2, 1)
    val nums2 = intArrayOf(2, 2)
    println(intersect(nums1, nums2).joinToString())
}

fun intersect(nums1: IntArray, nums2: IntArray): MutableList<Int> {
    val outputMap = hashMapOf<Int, Int>()
    val outputList = mutableListOf<Int>()

    for (i in nums1.indices) {
        if (nums1[i] in outputMap) {
            outputMap[nums1[i]]++
        } else {
            outputMap[nums1[i]] = 1
        }
    }

    for (i in nums2.indices) {
        if (nums2[i] in outputMap && outputMap[nums2[i]] > 1) {
            outputList.add(nums2[i])
            outputMap[nums1[i]]--
        }
    }

    return outputList
}

outputMap[nums1[i]]++

is complaining that

No set method providing array access

. I am not sure why.

Is there a easy way of getting maven dependensys in the Kotlin repl or is download and starting whit the -cp arg the only way?

I am just getting started with Kotlin.. How would I parse an XML file into a List of String? Coming from a C# background, the .NET framework was extremely rich with its parsing.

Hi people, I’m glad there’s a community channel to ask a question :D I’m a super newbie for Kotlin (I installed IntelliJ yesterday🙄) I have basics in Java by the way I’m just curious why println does not work inside for loop. Is this intended or is it just a bug in this IntelliJ IDE?

for ((index, element) in swarm.withIndex()){
     println("Fish at $index is $element")
 }
Fish at 0 is 12Fish at 1 is 5

Hi... I've been trying to find a solution to this - I was wondering if someone could work with me regarding this; rather new to Kotlin. I'm analysing a lot of words. I am trying to find the word which contains the most unique letters from (A-Z) and return it. Does anyone know a way to do this in Kotlin? I've been trying to for quite some time. Haven't seemed to find a way yet. Tom

Howdy, What would be the idiomatic Kotlin way to go here?

data class Calculation(
    val money: Double,
    val multiplier: Double,
)
fun Calculation.total(): Double = money * multiplier

OR

data class Calculation(
    val money: Double,
    val multiplier: Double,
) {
    fun total(): Double = money * multiplier
}

Howdy from Austin, TX.

What’s the best way to modify a nested property in an immutable data class object?

data class AppState (
    val masterState : MasterState = MasterState(),
)
data class MasterState (
    val isLoading : Boolean = false,
)

is there a more concise way than this?

val myState = AppState()
val newState = myState.copy(masterState = myState.masterState.copy(isLoading = true))

I would like to use a block function like this one inside an extension function:

fun MyModel.anExtensionFunction() {
	objectLambda {
	     it.getText()
	}
}

where it is the obj property of the MyModel class How should I write the objectLambda function in order to do so?

class MyModel {
    var obj = MyObject()
    fun objectLambda() {
         // HOW SHOULD I WRITE THIS FUNCTION?
    }
}

class MyObject {
    fun getText() = "myText"
}

How can I make the IDE to create this lambda for me? I hate myself writing that manually