can anyone give me initial direction for web scraping in Kotlin?

Hey all. I was hoping I could get some clarification about the

inline

modifier for functions. The Kotlin lang webpage for inline function states “Inlining may cause the generated code to grow. However, if you do it in a reasonable way (avoiding inlining large functions), it will pay off in performance, especially at “megamorphic” call-sites inside loops.” When it states that we should avoid inlining large functions, does this refer solely to the function receiving the

inline

modifier or does it apply to the contents of the lambda (which is being passed to the inlined function) as well?

Is there guidance as to when a property should be inlined (aside from needing reified parameter types)?

I currently have an object that prints out as such

Country(code=AD, name=Andorra)

but I need to convert it into json. Is there a stringify method or something I can use from kotlin stdlib in android? Most questions I look up on stackoverflow want me to bring in gson, but I really dont want to bring in a depedency for just this single little manipulation. Am I missing something basic here?

Hi, i am trying to understand more about Ktor and was wondering if there is any dedicated slack channel for asking question related to Ktor, thank you

hey folks! I’ve been playing around with annotations in this repo https://github.com/lucapette/konfig I’d love someone experienced in writing annotations to have a look at it. I found a bunch a config libraries but liked none of the api. So I thought this was a fun exercise. I’ll provide more context in the thread

Is there a standard lib function that takes an

Iterable

and returns true if and only if all items return the same value for a given lambda? I don't care what the value is. I know I can just apply lambda to first item and then use

Iterable.all {}

but I was wondering if there was a nicer way.

Hi everyone! I’m starting a new project and I was wondering which is the best practice to store an authentication token after a log in to use it in other api calls. Do you have any recommendations?

Today, I saw something that is new for me in kotlin's syntax. In https://github.com/zach-klippenstein/compose-fractal-nav, there is an interface

FractalParent

that is declared as follows:

internal interface FractalParent : FractalNavScope {
    // ...
    val zoomAnimationSpecFactory: () -> AnimationSpec<Float>
  // ...
}

and the class that implements the interface is:

internal class FractalNavStateImpl : FractalParent {
    // ...
    override lateinit var zoomAnimationSpecFactory: () -> AnimationSpec<Float>

my question is how he was able to override

zoomAnimationSpecFactory

and change its modifier from

val

to

lateinit var

without getting a compilation error?

Is there an equivalent to <Class>::new in Kotlin?

Is it possible to have a function invoked when an instance of a specific class is created in a class? Such as:

class SomeClass {
    val listOfThing = Array<Thing>()
    val thing1 = Thing()

    fun Thing.invoke() {
        listOfThing.add(this)
    }
}

Is it possible to have two instances of the same data class with the same exact properties (and values) be equal but not have the same hashCode? I thought if the two instances are equal then their hashCode should be the same

I have a problem with calling suspending functions from inside a lambda which is provided from an interface. More specifically, the interface has a function that looks like this

fun foo(lambda: Bar.() -> Unit)

. On one of the places where I call this, I happen to be inside a suspending function, where I want to be able to simply call on a suspend function like I normally would. This isn’t allowed since that lambda isn’t suspending, and I can’t make it suspending either. I see that this is solved in the vast majority of cases by having the function itself be

inline

which makes this possible, however I see that it’s not possible to define an interface function as inline. I’m sure this is something that others have faced as well, what are my options? I see that this is solved by defining them as extension functions to the interface like map is defined, but in my case I can’t do that either since the implementation of my interface wants to use some local variables when implementing this function.

Hey all - I'm trying to understand extension functions. I see the value in adding extension methods for other library authors code. However I'm trying to figure out the reason for doing so in your own code. I'm sure there is a reason because I'm seeing it a lot within the Ktor code base. I'm curious since the Ktor devs have access to their own code, why they didn't just add them as regular methods on a class. Would some one be able to shed some light on this? Thank you!

I have the following code:

object TestConfig {
  val ENV_UNDER_TEST by lazy { ... }
}

It’s a global variable I’m using in the project that stores the environment name under test. Is it possible to change that variable during the runtime? maybe with reflection or somehow else? I do understand that it’s not supposed to be changed and that it’s a dirty hack, so I accept that risk.

I want to get a list<String> of this enum class.

enum class BackendEnv(val humanReadableName: String) {
  STAGING("Staging"),
  PROD("Production")
}

How would you do it?

Hi, how can I set an argument of a data class as having a

internal set

?

Hi, I just ran into this quirky behavior combining if statement as an expression and elvis operator :

val nonNullVal = 
if(condition1) { 
    someOperation.get() // null 
} else if (condition2) { 
    someOperationTwo.get() // null 
} else { 
    null 
} ?: defaultVal

When condition 1 is true our

nonNullVal

evaluates to

null

. When condition 1 is false and condition 2 is true our

nonNullVal

evaluates to

defaultVal

What is happening? X_x I would just like to get a grasp of what is going on internally. Any help is appreciated! Thanks!

I’m extending a java class where I would like to override the getter/setter as properties is that really not possible?

class Sample<T> {
  @Nullable
  public T getValue() {...}
  protected void setValue(T value) {...}
  //...
}

That is the simplified base class I had in mind something like:

class Foo<T> : Sample<T>() {
  override val `value`: T
    get() {...}
    set(value) {...}
}

Currently building a Kotlin library for some NFC logic. How do I import the android.nfc.tech package so that I can use NfcV within the kotlin lib?

Why does that not compile?

@set:JvmName("setMyFoo")
@get:JvmName("getMyFoo")
open var foo: Int = 42

without

open

it works

Is it possible to set a conditional breakpoint on every String value created in a complex codebase and catch the creation of a specific String? (Regardless of which constructor to java.lang.String is used). I tracked down my specific bug but became curious on how to do it. Or can I get a creation trace via jvm flight recorder?

How can I use

is

with generics? For example if the generic is

<T : SomeClass>

how can check if T is a specific child of

SomeClass

?

Please can someone explain why this doesn’t compile:

interface Sequenceable<out T> {
    fun asSequence(): Sequence<T>
}

interface Item

interface TypeOfItem: Item

interface Items: Sequenceable<Item>
    
interface TypeOfItems : Items, Sequenceable<TypeOfItem> // Error message: Type parameter T of 'Sequenceable' has inconsistent values: Item, TypeOfItem

https://pl.kotl.in/BSez9qCNJ

I have this data class:

data class AttachmentItem(val imageId: String, val extension: String)

now I have two lists of these attachments:

val list1 = listOf<AttachmentItem>()
val list2 = listOf<AttachmentItem>()
//now I want to know which AttachmentItems are missing in list1 but are there in list 2 and vice versa. So:
val diff1 = //attachments available in list1 but not in list2
val diff2 = //attachments available in list2 but not in list1

How would I do that in kotlin?

Hi everyone! please help me, how can i get first 5 elements from from Map<String, Double> ?

Hi! I have a question! class :

data class MyDate(val year: Int, val month: Int, val dayOfMonth: Int) : Comparable<MyDate> {}

function:

fun test(date1: MyDate, date2: MyDate) {
    // this code should compile:
    println(date1 < date2)
}

Problem: I need to write a method for comparing MyDate objects I write a solution, it works ok

override fun compareTo(other: MyDate): Int {
    val yearDiff = year - other.year
    val monthDiff = month - other.month
    val dayDiff = dayOfMonth - other.dayOfMonth

    if (yearDiff == 0) {
        if (monthDiff == 0) {
            if (dayDiff == 0) {
                return 0
            }
        } else return monthDiff
    } else return yearDiff

    return 0;
}

and now “good” solution:

override fun compareTo(other: MyDate) = when {
    year != other.year -> year - other.year
    month != other.month -> month - other.month
    else -> dayOfMonth - other.dayOfMonth
}

i am not understand how works “good” solution? can you help me? what does mean

year != other.year -> year - other.year

Hi everybody, Is the logic of the delegate in C# and the delegate in Kotlin the same?

If I run

myFlow.collect { /* some work */ }

, is that work being done concurrently? If so, on how many threads? How do I control it?