Unfortunately the experimental Java-to-Kotlin converter is outputting 'garbage' results for me: • Nested comment blocks are being left un-matched resulting in half the output being 'commented out' • Confused output for properties e.g.

override var customText6: String? = null public get() {
    return field
  }

...is this ☝️ backed by a variable or computed? 🤦

Is there a way to get an invite to the iOS channel?

why is not not allowed to combine lateinit with custom setters?

As there are so many ressources about domain modeling these days, i had today a use Case where i thought it would make sense. I want to validate a Document and return a type ValidatedDocument Then i want to upload and only accept the type ValidatedDocument for it But my Problem is that ValidatedDocument can not only be created from my validation method but also just by calling the constructor. Is there sth obvious i am missing ?

data class Document(val uri: Uri)

data class ValidatedDocument(val uri: Uri)

fun validateDocument(document: Document): ValidatedDocument {
    val valid = true
    if(valid) {
        return ValidatedDocument(documentUpload.uri)
    } else {
        throw IllegalArgumentException("not valid")
    }
}

fun uploadDocument(validatedDocument: ValidatedDocument) {

}

fun main() {
    val doc = Document(uri = Uri.EMPTY)

    val validDoc = validateDocument(doc)

    uploadDocument(validDoc)
}

How to create a single parameter function that can take both

String

or

String?

as a parameter and returns simple

String

when called with

String

or nullable

String?

when called with

String?

?

What is the error in here?

Any solutions?

A bit of a language question:

data class

can't be extended (ok). If I chose to use an

interface

and implement it with a

data class

I can do things like this

interface MyPublicInterface {
  val x: String
  val y: Int
  val z: Whatever
}

data class MyImplementation(
  override val x: String,
  override val y: Int,
  override val z: Whatever
): MyPublicInterface

now this is ok, but if I do this then I can't use the useful

copy()

or

componentN()

functions method that comes along with a data class on my interface without casting it to my implementation. Is there some way to make my interface declare the

copy()

and

componentN()

? for the

componentN()

I guess it's possible by just defining the operators, but then I'd had to manually maintain them, still ok. But for

copy()

I've no idea how to do it

isnt possible to

@JvmName

a custom getter extender? (

val Bar.foo get() =..

)

Is there anyway to ensure a common indent for interpolated multi-line strings? Here’s an example:

val inner = """
    - List Entry 1
    - List Entry 2
""".trimIndent()

val outer = """
Outer:
    $inner
""".trimIndent()

fun main() {
    println(outer)
}

What I get:

Outer:
    - List Entry 1
- List Entry 2

What I want (expect):

Outer:
    - List Entry 1
    - List Entry 2

I am using a lof of Kotlin (for Android apps) and I would like to build some server-side apps. What would be your recommendation for server-side platform/frameworks/tools, ideally Kotlin based or at least tech something that it’s quite to switch from Kotlin (I am total noob here).

Anyone knows which font is used in the Kotlin logo? I thought it would be Helvetica, but as you can see the o is slightly off here

how do I write two dimensional array in kotlin? in php we can write it very easily, such as

$arr = [
    [
        "name" => "john"
    ],
    [
        "name" => "michael"
    ]
];

how do I achieve the above?

I have a class with some nullable properties

data class RequestModel(
    val description: String?
)

and a validation function

fun validate(model: RequestModel): RequestModel{
    if(model.description == null) throw IllegalArgumentException("description must be non null")
    return model
}

After this validation step, I need a way to indicate non-nullability of

description

property. One solution is to create a new data class which has non null propertis

data class RequestModel(val description: String)

. But I'm looking for a generic way to avoid creating new classes per use case. Ideal generic solution:

fun validate(model: RequestModel): NoNullableField<RequestModel>

How can I remove nullability from properties of a c.lass with nullable properties in a generic way? Is it usefull to use some kind of kotlin compiler contract? Link to SO question: https://stackoverflow.com/questions/59015821

Has anyone else has check the problem of data binding in unit tests: https://issuetracker.google.com/issues/117145132

what is the reason that kotlin does not allow

/

in a function name? e.g. `fun `/`` is not allowed but `fun `+`` is

Could someone please explain what it the key difference between these two options of the same function?

fun findShort(s: String): Int = s.split(" ").minBy { it.length }!!.count()

vs

fun findShort(s: String): Int = s.split(" ").minBy { it.length }!!.length

Both options work, pass unit tests and both are presented among solutions at codewars. Just trying to satisfy my curiosity ^^ Thanks in advance!

Is there any way to call

bar

here?

inline fun <reified A: Any?> foo() {
    bar(A::class)
}

fun <B: Any> bar(cls: KClass<B>) {}

This should be possible,

A::class

always returns the proper class, even if

A

is nullable. It looks like the compiler doesn't realize that (I'll probably report this on youtrack). Usually I'd just cast something but I'm not sure how to do that here, I want to cast to

A!!

but that's not real syntax of course. Any tricks?

Hey folks, I have a small issue with sequences. I have a CSV file parser which parses rows in batches. For each batch, it updates an input set object which contains information about the batching progress (failed rows, completed rows) and stores the updated input set and the parsed objects in our database. Here's the current code:

val inputSet = createInputSet(path, month, year, currentTimestamp)

val parser = BatchingDeclineRateFileParser(batchingConfiguration.batchSize, path)

return generateSequence { parser.parseBatch() }
        .map { batch ->
            val updatedInputSet = updateBatchedInputSet(inputSet, batch)

            transactionManager.runInTransaction {
                rateInputRepository.createAll(batch.batchItems, month, year, updatedInputSet.id)
                inputSetRepository.updateBatchStep(updatedInputSet)
            }
            updatedInputSet
        }
        .find { it.isProcessingDone } ?: throw JobException("Batch did not complete for some reason")

This works in general, but due to using map I only update the original input set each time. Is there a function on

Sequence

which works like e.g. ReactiveX's

scan

where I can fold the incoming values into an accumulator? http://reactivex.io/documentation/operators/scan.html

Hello, I'm new to Kotlin, and I want to use Exposed with it, but I'm getting

java.lang.NoClassDefFoundError: org/jetbrains/exposed/sql/Database

. Does anyone know how this happen and a solution for this? Thanks.

Does anybody know if Contracts (https://kotlinlang.org/docs/reference/whatsnew13.html#contracts) are close to leaving experimental (and if/how the final form is different from the 1.3 version)? I played around with the current version and immidiately have a feature request 😆 In Example 1 of the Contracts Proposal (https://github.com/Kotlin/KEEP/blob/master/proposals/kotlin-contracts.md#examples) they show a Smart Cast use case:

[Returns(true) -> x is String]
fun isString(x: Any?): Boolean = x is String

so I was interested in seeing if I can write a reified generic version (https://pl.kotl.in/XNSuwtkvC, which would be pretty useful for custom equals-methods):

inline fun <reified T:Any> T.hasSameClass(other: Any?): Boolean {
    contract {
        returns(true) implies (other is T)
    }
    if (this === other) return true
    return other!=null && this.javaClass == other.javaClass
}

Unfortunately currently this fails due to “references to type parameters are forbidden in contracts”. References to reified type parameters should be doable (<- my feature request).

seems https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md hasn't been updated for Kotlin 1.3.60 release

Hi guys, I have a problem with this code, I'm returning from repository a Flow<ListHouse>, the list has the house name and I want to filter it by a house name string that I have in my class. In my head filter is returning a new list with just one House so in map I am using first and get values (house values from potter api). But I always get all list house from filter so my first() in map always give me the values of the first house. I don't know why filter is not working with any(), they both are returning boolean from predicate (or at least I think so)

I'm looking for some guidance around boolean naming conventions in Kotlin. I'm working with an older java class which is populated from an API, where the API returns something like

canEditProfile

and the java class has a field named

isCanEditProfile

. I'll have a new kotlin class which exposes a few of these fields, and I think the name

isCanEditProfile

seems a bit odd, so I'm looking for alternatives for this and a few other similar booleans. I know

is*

and

has*

are commonly accepted boolean prefixes in the java/kotlin world, I'm just wondering if

can*

is also acceptable in this context?

Can i have your opinion regarding monitoring/listening location from android and iOS device and using the common to send the data to the server. (This is an MPP/shared library project). Im having a hard time since we dont have plugins or libraries that handles location from multiplatform project. Thanks!

I am having severe issues with custom lint checks. Performing

./gradlew clean lintDebug

sometimes include my custom checks and sometimes they do not. Same with Android Studio (inspections in the file are sometimes visible, sometimes they are not). I am having these issues in a rather large project - the same problems are not visible in an equivalent test-project. What should be the steps to see custom lint rules in action? Should just performing

./gradlew clean lintDebug

lead to the result we wish?

I'm still confused about what the "good way" to code in kotlin is, especially when I'm converting from the good ol' java code.

// autoconverted from java
    @Transactional
    fun leaveMembership(membershipNo: Long): Boolean {
        val membership = repository.selectOne(membershipNo) ?: return false
        membershipDeletedService.insertExpireHistory(membership)
        repository.delete(membershipNo)
        return true
    }

// futile attempt to use as much kotlin stuff
    @Transactional
    fun leaveMembership(membershipNo: Long): Boolean = repository.selectOne(membershipNo)?.let {
        membershipDeletedService.insertExpireHistory(it)
        repository.delete(membershipNo)
        true
    } ?: false

Which is more "kotlin-esque"? Or rather, which code do you think is better? If both are bad, how can it be refactored?

Hello, does anybody know why I’d get

NSInvalidArgumentException', reason: '*** -getValue: only defined for abstract class.  Define -[KotlinInt getValue:]!

error when using a Kotlin/Nativei library from Swift?

fun testMap(): Map<Int, Int> {
    return mutableMapOf(
        Pair(0, 1))
}