If I were to make a Kotlin Library project, how would I later on go about using it in a Kotlin Application project?

Is there an easy way to use TimeUnit class to specify 30 minutes for example? I found myself doing

val thirty_mins = 30 * 60_000

but there has to be a way to just do TimeUnit.Minutes(30) right?

Hi, I'm trying (and so far failing) to understand why evaluating the following code in a scratch file in idea results in unexpected (for me) output:

val l = mutableListOf("a")
l[0] = "b"
val x = l.first()
println("""$x=${l.first()}""")

⇒

val l: MutableList<String>

val x: String
a=b

When evaluated with "Use REPL" or via run command from the menu it prints "b=b" instead. Am I missing something or is this a bug? (If this is too intellij-specific and not getting-started-related enough, I'll be happy to move this to #intellij)

Questions on operator overloading. I am trying to overload the “+” operator to add to objects together but am given an error. However with my own add routine the function works. Could some one explain why? Questions on operator overloading. I am trying to overload the “+” operator to add to objects together but am given an error. However with my own add routine the function works. Could some one explain why?

class ArrayND  {
    var nDimensionalArray: ArrayList<Double> = arrayListOf()
    private var shape = arrayOf<Int>()

    constructor (ndArray: Array<Double>, shape: Array<Int>){
        nDimensionalArray = arrayListOf(*ndArray)
        this.shape = shape
    }

    private fun whatIsTheShape(): Array<Int> {
        return shape
    }

    fun add(b: ArrayND): ArrayND {
        if (shape.contentEquals(b.whatIsTheShape())){
            val x = arrayListOf<Double>()
            for(i in  0 until nDimensionalArray.size){
                x.add(nDimensionalArray[i] + b.nDimensionalArray[i])
            }
            return ArrayND(x.toTypedArray(), shape)
        }
        else {
            return ArrayND(arrayOf<Double>(), arrayOf<Int>())
        }
    }

    operator fun plus(other: ArrayND){
        add(other)
    }

    fun print(){
        TODO("Work in more than one dimension")
        print("[")
        for(i in nDimensionalArray) {
            print("$i ")
        }
        print("]")
    }
}

Hi, I now finished up the coursera course Kotlin for Java Developers. In there they do mention other courses, but I cannot find them on coursera. Does anybody know where I can find them?

Is it true kotlin executes on multi-core like Go?

Is it efficient solving problems using Immutability? Also is it possible to solve all the problem using Functional Style 🙂

Hi, when using the get() operator overload, what type of info do you get when you put multiple parameters in there? for example

val x = object[5,3]

What type of data is the 5, 3 representing.

hi there how can i add repository and dependency in my kotlin project?

What is the best way to check if any value in one array is greater that the value of another of equal size in each index?

I have a question about Intellij...what does the little blue square next to the folder represent? Project? Module? Library?

Similar to https://dbup.readthedocs.io/en/latest/

Can anyone please explain me what is

@IgnoreExtraProperties

in Firestore with an example?

On a specific class I want to define many methods (let’s say 50), but I want to group these methods in separate files by topic (let’s say files with 4-5 methods). I was able to achieve this by defining these “methods” as “extension functions” instead? Do you see anything particularly wrong with that?

And I want to do

call.respond(HttpStatusCode.OK,someJson)

and have the content type be

application/json

Going to do GUI for the first time in kotlin for a small project, what would be a good, relatively simple to work with framework?

Class type question? I have an untyped class in a class primarily holding a typed array hard typed to double. I would like to move it to type the class where the class property is the same type and am able to overload operators for handling different types of boxed primitives as well as different types of the class that I have build. What is the best way to move my untyped class to a typed class.

class ArrayND { // the class that I want to type
  var elements: Array<Double> // the array that all my functions refer too.
  var shape: Array<Int>
  constructor (ndArray: Array<Double>, shape: Array<Int>) {
    elements = ndArray
    this.shape = shape
  }
  operator fun plus(other: ArrayND): ArrayND {}
  operator fun plus(other: Double): ArrayND {}
}

I have a lot of functions that use array lists and convert them

.toTypedArray()

to create

ArrayND()

. This also has caused a problem when trying to be able to type the array and I would like to know if there is a way that if no type is given I could give it a default type of

Double

?

How do people tend to unit test DSL functions like the

address

function below? What are some good practices to handle the

Address.Builder

dependency?

fun main() {
    val address = address {
        street = "123 Any St."
        city = "Any city"
    }
    
    println(address)
}

fun address(lambda: Address.Builder.() -> Unit): Address {
    return Address.Builder().apply(lambda).build()
}

data class Address(
    val street: String,
    val city: String
) {
    class Builder {
        var street: String? = null
        var city: String? = null
        
        fun build(): Address {
            return Address(street!!, city!!)
        }
    }
}

Hello gang. Can anyone explain the kotlin artifact structure to me a bit? Specifically I’m interested in the kotlin-stdlib-jdk8 package. I’m creating a Quarkus app and I’m using Java 11 but it seems that I still have to declare a dependency on the -jdk8 package. As there is no -jdk11 package I assume this is all fine and correct… but I kind of want to understand what the idea behind this package is exactly.

What SQL clients are people using? I see https://github.com/JetBrains/Exposed is pretty popular (by GitHub stars), but it looks like you can't drop down to SQL without writing your own extension (albeit a simple one). Also, it isn't async. Is Exposed the preferred Kotlin SQL library?

Noob here when it comes to companion objects. I basically have a

class Blah {
companion object {
//HERE
}
fun somemethod2(){
//THERE
}
}

How can I define a variable that can be used in "HERE" and "THERE"? I know I can define

val MY_CONST

to the top of the file (outside of class declaration) but doesn't that make it global to all my classes? I just want it in the scope of the companion and the class.

I'm new to Kotlin and I would like to learn it. My current state of knowledge with other programming languages, is I have a good amount of knowledge of the concepts in Java (just never really wrote any complex projects, just know the concepts superficially). I also have my hands on a bunch of the resources on the kotlin website, but wasn't sure what would be best as my "first" real programming language. Any recommendations?

Is there some documentation on how to inspect a

CoroutineScope

/

CoroutineContext

? I would I unit test this function?

fun createCoroutineScope(): CoroutineScope = CoroutineScope(SupervisorJob() + Dispatchers.Default)

So in my test I have to check if the returned

CoroutineScope

is using a

SupervisedJob

or a particular

Dispatcher

how do I do that?? (or any other property of the context/scope)

Hello, I recently discovered Kotlin and IDEA and been loving them both. i'm currently using Kotlin for a project where I have an API that handles the business logic and, apparently, people at administration don't fancy doing cURL requests and want a web and an android client to consume it. Am I better off doing the api and the two clients each in a separate project, for three total, or all in kotlin multiplatform?

hi, quick question; what's the difference between

val foo
  get() = expensiveOrAllocFunc()

vs

val foo by lazy { expensiveOrAllocFunc() }

Hello everyone, I want to start android development. I just know basic syntax of Java like variable, data type, functions, loops, operators. I want to do android development in Kotlin. What should I learn now and what resources should I follow ? If you can show me a roadmap of Android development with Kotlin for a newbie that would be awesome.

Is there some way to declare an extension function that takes multiple (two) extension receivers?

<Can’t find a good answer in SO> What’s an idiomatic way to check if a list (or set) contains only one specific value? anything better than

checkedSet.contains(value) && checkedSet.size == 1

?

Generics question. I am trying to make a constructor where one value is accepted as

T: Number

and another value in the class is initialized as 0 but that type of Number. How do I do that?

class Complex<T: Number> {
  var real: T
  var imaginary: T

  constructor (real: T) {
    this.real = real
    imaginary = 0.ofType(T) // this is where help is needed
  }

  constructor (real: T, imaginary: T) {
    this.real = real
    this.imaginary = imaginary
  }
}