Invoking scala code from Kotlin File @engg.kanib wrote: Hi, I have a use-case where I want to invoke some functions that are written in Scala Object to be called from a kotlin file or Kotlin class. I am not finding anyway how to do it. I see that if the Scala is compiled ones separately then it gets called by the main in Kotlin file. But otherwise, it does not gets called. Can someone here please help me how can this be done?...

Multi platforms @O330oei wrote: Javascript HTML Jason Window Posts: 1 Participants: 1 Read full topic

Is it possible to have 2 annotation and generate 1 merge class based on the annotation in annotation processor @ptdede wrote: Let say I have 3 annotation class @Retention(AnnotationRetention.SOURCE) @Target(AnnotationTarget.CLASS) annotation class Combined ( val id: String ) @Retention(AnnotationRetention.SOURCE) @Target(AnnotationTarget.CLASS) annotation class Response @Retention(AnnotationRetention.SOURCE) @Target(AnnotationTarget.CLASS) annotation class Parameter my data class: @Combined("Request1") @Parameter...

Global variable assigned with applicationContext.filesDir @philippe.andrieu wrote: Hello, I am new in Kotlin. I have searched a solution on the web before posting this topic bit did not find one. I want to to set a global val variable (vDataFile) at startup that I want use in any function in the MainActivity class but the program crashes when reaching that second line. Could anyone tell me what is wrong? class MainActivity : AppCompatActivity() { val...

Kotlin/JS: Unable to load Kotlin-Styled, kotlin-css-js @cchunduri wrote: Hi, I’m preparing a talk on how to use Kotlin/JS for React JS applications. For the demo purpose i’ve created a project, and here is the link to my project, https://github.com/cchunduri/kotlin-js-demo But when i’m running my project i’m getting below errors ERROR in ./kotlin/kotlin-js-demo.js Module not found:...

Why could coroutines swallow exceptions? @Balage-1551 wrote: I am just started to use coroutines and I like the concept and tools very much. However, even within my few weeks of practice, I ran into a problem twice. In some circumstances, an uncaught exception thrown within a coroutine is simply swallowed and not printed out at all. I simply can’t find any cause justifying implicit hiding of an uncaught exception in any way. I am sure there is a...

Retrofit unable to resolve host @HydraRock wrote: Hello, I am trying to call an API through retrofits. The url that I call, is located on a server, in which at this moment I access go VPN. The token I am sending right now is good. I have tested everything via postaman and it works correctly. Instead when I call through Android studio I get the exception “retrofit unable to resolve host”. I have made various changes to the code, according to...

Simple Tree Implementation: Why MutableSet equality returns false for what seems to be the same sets? @TheBestPessimist wrote: As I’m learning Kotlin, I’m trying to implement a simple Tree. The problem is my equals implementation is buggy, and i can’t figure out why I have a node class with autogenerated by intellij equals class Node(val value: String) { var parent: Node? = null val children = mutableSetOf() var depth: Int = 0 fun addChild(child: Node) { children.add(child)...

Unit Tests for android and common module not working @wMan wrote: Hi, I setup my mpp (ios/android) by following instructions of this article https://medium.com/better-programming/a-multi-platform-library-with-kotlin-episode-1-6c0f46d49944 Everythink is working except unit tests for android and common module. Unit tests for ios module...

Newbie Question @venacava19 wrote: sorry for a very dumb question, I’m trying to build an app using kotlin language but I’m having a difficulty simplifying my code: i am just self learning here is my sample code do { val b = mutableListOf() val b2 = (1..5).map { (1..15).random() } val b3 = b2.distinct() if (b3.count() == 5) { for (n in b3) {...

Be able to return vararg T @nanospicer wrote: The proposal is very simple; be able to return vararg of something as a type. Rather than this being a need (because you can always return a list or provide a list builder) I believe it would look very JSONy while designing DSLs. And maybe I am biased but I like it better with the lambda syntax than using the parentheses fun notificationChannels(channelProvider: () -> (vararg...

Can I force the caller of a function to process the return value? @kotlinikov wrote: I’m funneling exceptions through a result type, but this funneling is not of much use if the caller can ignore the result value of the funnel function. Is it possible to define a function such that the code won’t compile unless it is explicitly assigned to a variable? Example: fooBar() // this won't compile val r = fooBar() // this will compile Posts: 1...

Why return type of producer methods in projected generic types with upper bound is Any? instead of upper bound type? @Ehsan wrote: I asked this question here on Stack Overflow and didn’t get any answer. Consider this setup: open class Base open class Derived: Base() interface Foo { fun produce(): T fun consume(aT: T) } Following functions are valid: fun...

While loop with multiple conditions @stanislav.sst wrote: Hello all! here is a code: fun test() { var a: Int var b: Int var c: Int var result: Double do { a = Random.nextInt(1, 1001) b = Random.nextInt(1, 1001) c = Random.nextInt(1, 101) result = (a.toDouble() - b.toDouble()) / c.toDouble() } while (((result - result.toInt()) != 0.000) && (result 0 and reminder = 0. It seems that these both conditions in while loop cannot be...

Runing Kotlin Script through Gradle @TopHatCroat wrote: Hello, I am trying to run a .kts file through a Gradle task. I’ve followed this gist and I managed to get it working on Kotlin version 1.1.0, but when running it with version 1.3.70 it gives back error: unable to evaluate script, no scripting plugin loaded. I’m not sure what this error...

Java 9 StackWalker @Strum355 wrote: Hi, I don’t seem to see how I can use the Java 9 StackWalker features. If anyone has any ideas or explanation why it may not be available, I’d be delighted to hear StackWalker javadoc Posts: 1 Participants: 1 <a...

A more efficient (yet still succinct way) to create a freq. map? @stenlee wrote: Suppose I have a collection of (not necessarily distinct) values, And I wish to calculate a ‘frequency map’ for that collection. I figured out a way to do it, using groupBy and then map and toMap: val values = arrayOf(1, 1, 1, 2, 3, 4, 4) values.groupBy { it } .map { (value, eqVals) -> (value to eqVals.size) } .toMap() // res0: kotlin.collections.Map = {1=3, 2=1, 3=1, 4=2} My question is: Is...

[stdlib] Is there a date-time / ISO-8601 API planned for the future? @alexis.manin wrote: Hi, Sorry in advance for the broad question. What support is there now, and what is planned to be in the future concerning date and times in stdlib (something like java.time - formerly joda - but even better xD) ? Is that an identified need/evolution ? Or is it planned to be delegated to third-party libraries ? What I’ve found in official doc looks like it’s strictly focused on time...

Kotlin 1.4-M1 Typescript Definitions and React @avwie wrote: Okay, so I am experimenting with the Kotlin 1.4-M1 pre-release, and am fully aware that it is beta. However, on reading that it can generate .d.ts files I was so excited I started a very small Hello World example. But no matter what I try I can’t get it to work in a React Typescript project. The modules are undefined, or something else is not found. I tried nodejs() target, browser() target, tried...

Kotlin fails to find extension functions and type aliases @Russell wrote: I run into this frequently. Usually, changing an import fixes it for me until today. Example problem: package test1 enum class Foo { ONE TWO } package test2 import test1.Foo fun main() { // Code references "Foo.ONE" // That works } package test2 import test1.Foo import test1.Foo.ONE fun main() { // Code references "ONE" // That fails } When this happens, I’m usually updating...

Triggering event with two parameters @Spireoso wrote: My problem is apparently simple, but could not find any simple and working solution on the web. I want to trigger an event with two parameters in a customized class (Fruit in the example below) and handle it in the MainActivity class. How is it done? class Fruit @JvmOverloads constructor( context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0 ) :...

I'm Newbie In Development @instagber wrote: I’m really newbie in the android development. Can you give advices for me, while i was watching my udemy lesson, i could catch the codes and basics. After that, when i try to build some basic projects for improve my skills, it gets hard. I have many syntax errors. I know what to do, but I’m confusing the order. What can i do to do get better ? Posts: 1...

Call OpenCV functions from Kotlin Native @hasan.oryx wrote: In this and this the author explaining how to call OpenCV functions from C#. How can I do this from Kotlin Native? <a...

Secondary constructur with JVM signature conflict @roland.schuetzig wrote: The following little code produces an error in IntelliJ IDEA. class A(fct1: (Int) -> Float = {0.4f}) { constructor(fct2:(Int)->Unit) : this() } The compiler perceives fct1 and fct2 as a conflict, allthough they have different types (Int)->Float and (Int)->Unit respectively. Isn’t it the philosophy of Kotlin to take care for exactly that sort of thing? fct1 and fct2 are just...

Wrapping the call Context.getString with formatting arguments results in a IllegalFormatConversionException @nanospicer wrote: Essentially: I can’t manage to format a String obtained through the Context object. I’ve tried a couple of things. Check the StackOverflow question I wrote a couple of days ago stackoverflow.com <a...

First Kotlin steps (maven question) @sallmard wrote: I’m aiming to learn Kotlin - I’ve loved what I’ve seen so far. I created a Maven project using the jetbrains-kotlin-jvm maven artefact, tried to build, and immediately get an error: Please add kotlin-script-runtime.jar to the module dependencies why would something so basic be missing? I’d like to end up with a working Maven project, use apache POI and some data science kotlin modules and get...

Converting from java @jsoneaday wrote: How do I convert this Java to Kotlin DataFetcher userDataFetcher = new DataFetcher() { @Override public User get(DataFetchingEnvironment environment) { // environment.getSource() is the value of the surrounding // object. In this case described by objectType User value = EntityData.Companion.getUser(environment.getArgument(“id”)); // Perhaps getting from a DB or whatever return value; } };...

How to access an enum class from another file (which is also a class)? @harrywyt428 wrote: This is my code for the enum class: package me.core enum class RateLimitPrecision(val value: Int) { Seconds(0), Milliseconds(1); companion object { fun from(findValue: Int): RateLimitPrecision = RateLimitPrecision.values().first { it.value == findValue } } } And I want to access this by assigning a variable: var RateLimitPrecision =...

Sequences and Inlined Lambdas @derektom14 wrote: Suppose you want to do the very common operation of applying a filter and a mapping to a list, and you want the code to be very efficient. The most obvious first solution is to write: val processedItemNames = items .filter { it.isProcessed } .map { it.name } This is the most concise code, but with a catch that both filter and map create new lists. After the inlining is done, the...

Scoped variable assignment used inside if statement @guangyya wrote: Hi there: I am currently working on an Android project using both Kotlin and C++, one thing I think pretty good about the C++ syntax is the scoped variable inside if statement. For example: if (auto controller = getController()) { controller.do(); } else { // controller ptr is invalid here and outside if statement } is there any similar way for kotlin to do so? one possible way in my head is:...