Hi 👋 Quick question: When developing a library (in my case an Android library), how do I know with which other Kotlin versions it will be compatible? E.g. when I am using latest 1.7, will a consumer of my library that uses Kotlin 1.5 have issues?

are there any good encryption/decryption libraries in kotlin/JVM for storing license file information(perhaps specific to a given hardware/platform)?

is there something like

val myVar by lazy{ something() }

, but does not cache the value, but re-evaluates the value every time

myVar

it is access?

myVar

is a local variable

I want a

sealed class

where children share some common variables. how do I do this with the least amount of boilerplate? what I was recommended is something like

sealed class Parent {
    abstract val s: String

    data class Derived1(override val s: String, ...) : Parent()
    data class Derived2(override val s: String, ...) : Parent()
    
    sealed class Derived3() : Parent() {
        data class Derived4(override val s: String, ...) : Derived3()
    }
}

which repeats the

val s

declaration

There's no trivial way to make a

value class

expose all its value's members at the top level is there?

Hi, is it a problem to have a package contain the word internal? ex:

com.company.internal.feature

?

Hi 🙂

import com.fasterxml.jackson.annotation.JsonProperty
import com.fasterxml.jackson.module.kotlin.readValue

data class InsideList(
    @JsonProperty("price") val price: String,
    @JsonProperty("product") val product: String
)

data class NList(
    @JsonProperty("listexample") val listexample: List<InsideList>?
)

the

response

is the json list

val jsonResponse = MapperUtility.jsonMapper.readValue<NList>(response)

println("Response : {${jsonResponse.listexample}}")

the print is:

NList(listexample=[InsideList(product=apple, price=ten)])

how can i print just the value of the product? i tried to do it with

forEach

but not works as expected 🙄

Whenever I refactor Kotlin code in Android Studio and I get an automatic suggestion to rename some class properties, the suggested names all start with

m

in the old Java naming convention:

mSomeProperty

. Can I configure it somewhere that Kotlin refactoring doesn't use (obsolete) Java naming conventions?

Conceptual question here. I have a class which contains a list. Whenever the size of the list is 1, I want certain functions to be used, and when it's greater than 1, I want alternative functions (which serve the same purpose but do something a bit different) to be used. (it's a Java swing app in kotlin so lots of gui stuff). What sort of structure should I use to keep this organized?

Why I can't access a method whose receiver is Test inside the class Test2 when inside a builder with Test ? But I can adding

with

of my instance of Test2.

class Test(var name: String = "test")

class Test2 {
    fun Test.method() = name
}

fun builder(block: Test.() -> Unit) = Test().apply(block)

fun main() {
    val a = Test2()
    
    builder {
        with(a) {
            println(method()) // can access method()
        }
        println(a.method()) // cannot access a.method() for some reason ?
    }
}

How do you type maps properly in Kotlin? I want to make a type that is a map with two required keys. tried using class, but I am at a loss.

abstract class GameState(i: Int, i1: Int) {
    abstract val pinsLeft: Int
    abstract val triesLeft: Int
}

fun roll(pinsDown: Int,
         pinsLeft: Int = 10,
         triesLeft: Int = 2): GameState {
    return mapOf(Pair("pinsLeft", pinsLeft - pinsDown), Pair("triesLeft", --triesLeft)
}

The problem is that the typing system doesnt know if a key gives back a value in my map (which I use to store my state):

@Test
fun `Roll returns how many pins are left when rolling 0 twice`() {
    val state = roll(0)
    assertEquals(0, roll(state["pinsLeft"], state["triesLeft"])
}

Is this climbing uphill with Kotlin? Should I just create my own datastructure GameState with getters, constructors and setters? Or is there a good way to do this with the inbuilt map structure?

Is this a viable approach?

data class GameState(val i: Int, val i1: Int) {
    private val pinsLeft = i
    private val triesLeft = i1

    operator fun get(s: String): Int {
        when (s) {
            "pinsLeft" -> return pinsLeft
            "triesLeft" -> return triesLeft
        }
    }
}

Hi, does someone knows how to defined a function of any type in kotlin ? no matter what the param and return are . In typescript, we can do it like this:

type Fn = (...args:any[]) -> any

but I don't know how to do it in Kotlin.

I'm looking at the Icons declaration in compose, an i have a style question. Right now the icons declaration looks like this:

public val Icons.Filled.Circle: ImageVector
    get() {
        if (_circle != null) {
            return _circle!!
        }
        _circle = materialIcon(name = "Filled.Circle") {
            materialPath {
                moveTo(12.0f, 2.0f)
                curveTo(6.47f, 2.0f, 2.0f, 6.47f, 2.0f, 12.0f)
                reflectiveCurveToRelative(4.47f, 10.0f, 10.0f, 10.0f)
                reflectiveCurveToRelative(10.0f, -4.47f, 10.0f, -10.0f)
                reflectiveCurveTo(17.53f, 2.0f, 12.0f, 2.0f)
                close()
            }
        }
        return _circle!!
    }

private var _circle: ImageVector? = null

And i wonder why doesn't it just use lazy initialization? As in something like this:

public val Icons.Filled.Circle: ImageVector by lazy {
        materialIcon(name = "Filled.Circle") {
            materialPath {
                moveTo(12.0f, 2.0f)
                curveTo(6.47f, 2.0f, 2.0f, 6.47f, 2.0f, 12.0f)
                reflectiveCurveToRelative(4.47f, 10.0f, 10.0f, 10.0f)
                reflectiveCurveToRelative(10.0f, -4.47f, 10.0f, -10.0f)
                reflectiveCurveTo(17.53f, 2.0f, 12.0f, 2.0f)
                close()
            }
        }
    }

Is it just a style issue? Or the second approach has hidden performance cost?

Hi all, Im new to android development and going through this tutorial and getting hung up on this step

sqldelight {
    database("AppDatabase") {
        packageName = "com.jetbrains.handson.kmm.shared.cache"
    }
}

while using Android studio, I’m not able to create a package like that, but directory instead, that looks like this.

sqldelight {
    database("AppDatabase") {
        packageName = "com.example.ktorSQLDelight.shared.commonMain.sqldelight.shared.cache"
//      packageName = "com.example.shared.cache"
    }
}

i called this project ktorSQLDelight, i tried the above, but my AppDatabase is never “found” by the rest of the app.

i have tried any combination of that path without avail

I don't suppose there's a way to abstract the declaration of the fields on an anonymous object is there?

I'm looking for a way to calculate image similarity in Kotlin using cosine similarity. Does someone know a lib where this algorithm has already been implemented? The next best thing I was able to fnd is only a image hashing algorithm in Java which I could rewrite in Kotlin using skija. As far as I understood the cosine similarity algorithm has better results than image hashing, but I'm unfortunately now even able to find a Java implementation of this.

Is

String

a primitive type ? if so , why I can use

lateinit

on it but not on

Int

? the doc(https://kotlinlang.org/docs/properties.html#late-initialized-properties-and-variables) says

The type of the property or variable must be non-null, and it must not be a primitive type.

I got a error like this

I have already checked, but just to be sure, allow me to ask: is there an immutable deque in Kotlin. There's ArrayDeque but it is not immutable. I am using LinkedBlockingDeque (a java implementation), but want to replace it with an immutable one.

Do you know any workaround to use objects with ServiceLoader? It requires a non-arg constructor, otherwise it will fail:

Caused by: java.util.ServiceConfigurationError: Factory: Impl Unable to get public no-arg constructor

and

NoSuchMethodException: Impl.<init>()

Is it possible to give a more specific deprecation suppression here? I have had no luck putting just

@Suppress("DEPRECATION")

anywhere

$ cat Test1.kt 
@file:Suppress("DEPRECATION")

import foo.Bar
$ cat Test2.kt
package foo

@Deprecated(message = "Bar is deprecated")
interface Bar
$ kotlinc -Werror Test1.kt Test2.kt

Hi, I want to define a factory for an interface for a common library. I want to understand the pros/cons of defining a concrete class vs using anonymous object. Can’t wrap my head on the lines in Object expressions regarding anonymous classes:

Such classes are useful for one-time use

.

interface Person {
    val name: String
    val age: Int
}

Option 1
---
fun Person(name: String, age: String): Person = object : Person {
    override val name = name
    override val age = age
}

Option 2
---
fun Person(name: String, age: String): Person = PersonImpl(name, age)

private class PersonImpl(
    override val name: String,
    override val age: String
) : Person

1. What’s the pros/cons between the two? 2. Which is more preferred? 3. What does

one-time use

mean? Does it mean we can’t pass instances of anonymous classes around?

when debugging Kotlin with IntelliJ, is it possible to go back to some point in a previous frame?

How can i exclude data class field from hash code and equals?

Is there any particular reason why companion object should be at the bottom? Or it’s just a convention ?

When is the release of Kotlin 1.8.0 planned?

hi! i’m new to kotlin and KMM and i’m trying to create a multiplatform app using this android library but i’m still confused about how to setup everything. i even opened up a stack overflow ticket about it but i’m still not clear about how it works? i’m supposed to add the dependency in the androidApp module and then create a common api in commonMain and then platform-specific code in iosMain and androidMain?