(argument as List<String>?)?.orEmpty()

intellij is highlighting the

?.

as "This call is useless" why is it useless?

guys i am new here what is the best place to learn kotlin and ye expect kotlin

is it a better way of doing this? I would expect something like a

guard

in swift

Can kotlin have function to do this?

I’ve created an intellij project with Kolin-JVM used. But when I type in GlobalScope to do coroutine stuff its pointing to javax.xml.bind.JAXBElement how can I solve this?

can someone explain why a++ works in a string template but not a+=1

To simplify the compiler code.

if I want to use generics in function definition, do I must need to put a <T> before the function's name like fun <T> whatever(x: T, y: T) ?

Hi guys, I want to start kotlin multiplatform i want to make a shared network library which can be used in android, IOS and web like JS etc, can you please give me a tutorial or anything which covers all platform?

how can I get a reference to a top level function from a string, e.g. the name of the function

can i instantiate

class Foo

from

Foo::class

in any way?

is there any specific reason for that

This might be a dumb question but where are the method bodies for the operators functions inside Primitives.kt

is it possible to add annotations to variables defined in interfaces? i.e

interface foo {
    @StringRes val text: Int
}

TIL that

MyClass::class.sealedSubclasses

does not return the classes in the order they were defined as opposed to

MyEnum.values()

in Java. Bit me!

one thing I don't get about REPL: Since it evaluates expressions, shouldn't "print("Hi")" display "Unit" instead of "Hi"?

In Kotlin, can every expression (theoretically) be used as a standalone statement? Java doesn't allow putting 1 + 1; into a line but in Kotlin that works

In Kotlin, assignments are not expressions. But aren't increment and decrement operators also assignments technically?

How do we add generic class as Map value ? I am defining class named

abstract class CardHolder<T:RecyclerView.ViewHolder>{

    lateinit var actionListener: CardActionListener

    abstract fun onCreateViewHolder(parent: ViewGroup): T

    abstract fun onBindViewHolder(holder:T, card: Card, position: Int)
}

which will be extended to do inflationa and other formalities to display data,

class NewCardDelegate:CardViewHolder<NewHolder>{
	//Rest of code
}

the reason I was doing this so that I could define a mutableMap<Int,CardHolder> and reduce the Adapter class

val map =mutableMapOf<Int,CardHolder>
map[25] = NewCard() //error

but it seems like its not right way Please guide me for any other better way

“”” open class Base(p:Int) class Derived(p:Int): Base(p) “””

why this derived class have p?

Is this function “returning an object of type Dispatcher, but since Dispatcher is an abstract class I have to use the object keyword and declare that object as an instance of the abstract class?” 😐 not sure about this part:

: Dispatcher = object : Dispatcher()

fun updateErrorCodeForUrl(url: String, errorCode: Int) : Dispatcher = object : Dispatcher() {
        @Throws(InterruptedException::class)
        override fun dispatch(request: RecordedRequest): MockResponse {
            when (request.path) {
                url -> return MockResponse()
                    .setResponseCode(errorCode)
            }
            return MockResponse().setResponseCode(422)
        }
    }

Am I creating a race condition with the coroutines when I write

val job = GlobalScope.launch { /* Things here */ }

then

job.invokeOnCompletion { /* It's done now */ }

? What's the best way to handle this?

what parts of the project can REPL access? Only the functions?

i.e. is there some way that Kotlin could be intelligent about automatic SAM conversion, without the need for extra boilerplate?

I think this is a basic question, but why can I assign properties to data created with`val`?

val intent = Intent(Intent.ACTION_VIEW)
intent.data = Uri.parse(platform.appUrl)

I have a rudimentary question.

fun foo() {
    getData()?.let { data ->
        doSomething(data)
    }
}

Is it equivalent to this?

fun foo() {
    val data = getData() ?: return
    doSomething(data)
}

I don't like adding more indentations, so came up with the second one. Is it OK?

Hello ! I'm in need of advice. I'm trying to get a list of chapters from webfictions. When I'm sending a list of IDs (part of URL for retrofit to dl the chapter), it is an ordered list. I want to be able to download all chapters asynchronously (in case some download faster than others), but still keep the order from the first list (first in the chapterIds list will be the first in the return List<Chapter>, etc...). Is it the proper way to do this, or I'm going at it completely the wrong way?

suspend fun getChapters(chapterIds: List<String>): List<Chapter> =
    mutableListOf<Chapter>().apply {
        chapterIds.forEach { launch { add(getChapter(it)) } }
    }

suspend fun getChapter(chapterId: String): Chapter {
    val response = service.getChapter(chapterId)
    return if (response.isSuccessful) {
        val doc = Jsoup.parse(response.body()?.string())
        Chapter(
            doc.select(CHAPTER_TITLE_QUERY).text(),
            doc.select(CHAPTER_CONTENT_QUERY).html().lines()
       )
    } else Chapter()
}

I have

val articles: List<ArticlesItem?>? = null

as part of my JSON response. I am trying to pull data off this list using

articles[position]

but Android Studio complains that

Only safe (?.) or non-null asserted (!!.) calls are allowed on a nullable receiver of type List<ArticlesItem?>?

. Why can I do

newsDataSet!![position]

but not

newsDataSet?[position]

?

val articlesItem: ArticlesItem? = newsDataSet[position]

full code https://github.com/sudhirkhanger/Samachar/blob/911f934252409e9a726e30a4865518e738042c93/app/src/main/java/com/sudhirkhanger/newsapp/ui/list/NewsListAdapter.kt#L45

Hi! I have enum like this:

enum class Events {
    "one",
    "two",
    "three"
}

And I need to get List<Map> like this:

({name: "one", id: "one"}, {name: "two", id: "two"}, {name: "three", id: "three"})

Is there idiomatic way to do this? No ‘for’ loop.