I have some listeners:

typealias Listener<T> = (T) -> Unit

and for each

T

that I accept I need to store the list of registered listeners:

val userListeners = mutableListOf<Listener<User>>()

. But this forces me to have N lists for N possible

T

. Is there a better way?

This is very interesting:

Class<PersonKotlin> klass1 = PersonKotlin.class;
KClass<PersonKotlin> kotlinClass1 = JvmClassMappingKt.getKotlinClass(klass1);

Class<PersonJava> klass2 = PersonJava.class;
KClass<PersonKotlin> kotlinClass2 = JvmClassMappingKt.getKotlinClass(klass2);  // error

Although the types of

klass1

and

klass2

are identical the compiler recognizes that I can't call

getKotlinClass

on a Java class. How does it do that?

So, I have some legacy java code that I don’t want to touch, but I would like to add some Kotlin extensions around it to make it easier to work with. The terrible java side (as far as I am constructing it) looks like

Criteria criteria = new Criteria(new Filter(new Filter.FilterConditions("field", "value", FilterConditionOperator.EQ)))

The “FilterConditionOperator” thing really annoys me - and I don’t think I’ve seen a way to sort of “force a static `import`“, right? Would the “idiomatic Kotlin” way to go be maybe to make an infix function for each of the enum values, as a FilterConditionFactory?

Why can't I check at runtime if

Listener<T>

is

Listener<User>

?

@Michael Define the function in the dsl class?

anyone knows who manages https://kotlin.link/?

Anybody here have a hard time with compiling big projects in Intellij using kotlin/gradle? I mean like 3-10 minute compile times.

(Mind you, I haven’t use Gradle!)

how can I get corresponding

java.lang.Class

from

kotlin.reflect.KClass

?

is possible to make a binding of Flutter Engine to Kotlin Native?

Beginner kotlin developer here. In swift land, when I wanted to create constants I would declare an enum which contains static variables:

enum Constants {
    static let randomNumber: Int = 42
    static let randomString = "42"
    static let randomNonPrimitiveType = CustomClass(number: 42)
}

Then use it like so:

let constantsUse = Constants.randomNonPrimitiveType

What’s the best way to do this in Kotlin? Especially if the constant is a non primitive type.

oho... interesting 🙂

So my question is, someone knows if we have an starter project to create multiplatform kotlin apps? Or other projects like this kotlinconf app with multiplataform branches (using all kotlin possibilities)?

for the sample, “singletonReadOnlyList”, and for the documentation: “..an immutable list containing only..”

Hi guys. Someone knows a good way (preferably using IntelliJ) to convert spaces identation to tabs in the entire project?

Hi fellow kotlin devs, does anyone of you know if its possible to put class level annotations on a global function? Do I miss something or is it simply not possible?

@Danilo You can add a formatter profile containing just that rule and reformat the whole project.

class Conference<T>(val mainOrganizer: T) { fun addSpeaker(speaker: (? extends T)) { } }

My coworker Erica just filed a really interesting issue if anybody feels like checking it out:

In my package

a.b.c

, I have an

abstract

class named

BaseUser

which I use it to share some code. But I want this class

BaseUser

to be internal in the

a.b.c

. Such that, I can create

User:BaseUser

in

a.b.c

. But the user of package can’t refer

a.b.c.BaseUser

. I tried the

protected

modifier. Not work, when I try to build, it said

This type is final, so it cannot be inherited from

,

Cannot access 'BaseUser': it is protected in 'a.b.c'

and

'public' subclass exposes its 'protected (in ?)' supertype BaseUser

. No luck with

internal

too How to make this work? 🤔

Any ideas to solve the problem? I have also tried the IntelliJ 2018.1 or Kotlin plugin versions from 1.2.10 to 1.2.40dev and none of them works.

The only change is just

Exception e

->

e: Exception

Hello everyone! is there a way to use Kotlin Preconditions checkNotNull() and have a smart cast for the checked variable?

This message was deleted.

Is there a way to pass an array to a function that takes a vararg parameter? The spread operator passes a copy of the array, not the array itself. I encountered this problem when reading the docs of `Arrays.asList`:

Returns a fixed-size list backed by the specified array. (Changes to the returned list "write through" to the array.)

But it looks like using this property is not possible from Kotlin since you can't pass the real array.

what is the correct way to wait for a thread to finish? Is this ok or is there a better way to do it ?

val mythread = thread { .... some code here that runs in this thread ... }
... more code here ...
while (mythread.isAlive) {
    Thread.sleep(10)
}
do something else that depends on things setup during the thread

is there are nicer way of writting the following:

val list = mutableListOf()
var parent = map[current]
while(parent != null){
  list.add(parent)
  parent = map[parent]
}

I have the feeling there is a functional equivalent but I cannot come up with what it is

This message was deleted.

should I do

sealed class Foo { object BAR : Foo() }

or

sealed class Foo { object Bar : Foo() }