Hello, World! I want to enhance the

toString

of some class that belongs to a dependency. For that I'll make an extension, but can't call it

toString

for obvious reasons, and I'm not very inspired, can you think of a good name?

betterToString()

/

toExtraNiceString

/

toEnhancedString

/

toDetailedString

... Better ideas? 🙏

What are the advantages/disadvantages of the atomicFu

ReentrantLock.withLock {}

vs. the coroutines

Mutex.withLock {}

?

It seems like there's still an outstanding issue in Kotlin, with regards to data classes with private constructors. The basic problem being that the copy method allows you to still set the members individually, and is always public, and cannot be deleted. This means that currently in Kotlin it doesn't really seem possible to write a data class in Kotlin that has any invariants amongst members which are part of its representation, which is annoying if you primarily want the data class for hashing or equality, for example. What's the recommended practice around this for now, and what direction is it headed in the future?

Hi 🙂 is here anyone who knows spring? I need advice

I am getting error: The feature "unit conversion" is disabled. What does this mean? and how do I enable it? IDEA suggested to set languageVersion to "1.4", I am still getting the error though

This is the stdlib implementation of MutableMap.getOrPut

public inline fun <K, V> MutableMap<K, V>.getOrPut(key: K, defaultValue: () -> V): V {
    val value = get(key)
    return if (value == null) {
        val answer = defaultValue()
        put(key, answer)
        answer
    } else {
        value
    }
}

It seems like either the implementation or the description is wrong:

Returns the value for the given key. If the key is not found in the map, calls the defaultValue function, puts its result into the map under the given key and returns it.

println(mutableMapOf<Int, Int?>(5 to null).getOrPut(5) { 10 })

Prints 10. However, 5 is "in the map" (

println(5 in mutableMapOf<Int, Int?>(5 to null)

prints true). kotlin nulls are very tricky in generic code.

why is transform in Map.mapValues defined as

transform: (Map.Entry<K, V>) -> R

instead of just

transform: (V) -> R

?

Can we use current versions of coroutines and serialization with 1.4.30-M1?

Hey guys currently out of a Job 😩, but good news is I am willing to volunteer with any who needs help on a project 🙏.

Hey what does the colors signify in IDE for example Android Studio: For yellow and white over here

Hello every one can anyone help me with How to get list of videos from specific folder in android ?

In the coroutines documentation, it's stated about

join

(link) that if called on a coroutine that's cancelled, it will throw an

CancellationException

. However, in this example from the official docs,

job.join()

is called right after

job.cancel

, yet it does not throw anything. Why not ?

Is there a better name for a class that has these properties?

Hello. Are there

StateFlow

builders similar to

callbackFlow

? I'm trying to transform this code to use a

StateFlow

instead of a `Flow`:

fun <T> ObservableValue<T>.values(): Flow<T> = callbackFlow {
    val listener = javafx.beans.value.ChangeListener<T> { _, _, newValue ->
        offer(newValue)
    }

    addListener(listener)

    awaitClose { removeListener(listener) }
}

I'm trying to import the atomicfu plugin using Gradle, but the dependency is unresolved. Do I need a particular repository?

Hi everyone The wibinar of today is not available in the YouTube channel what's happened

Would union types in Kotlin, instead of overloads be possible in the future?

an example of union types in kotlin would be

fun union(message: String | ByteArray)

May not be specific to kotlin but I am trying to add some unit tests that run independent of regular tests, ideally the "test" gradle task would skip these but another task would run only those. How can I do this aside from adding another project just for testing?

How do I add multiple -Xopt-in flags in gradle?

Hi, I'm experiencing an issue with the official code style in IntelliJ. Some times it seems to override my preferred code style with this one. And the two styles are quite different, so it is very jarring when it happens. Is there any foolproof way to make sure it does not randomly revert back to the stock code style?

Hi, I'm looking for a good explanation of cold and hot Flows in Kotlin, i feel like I don't really understand the concept and implementation from the ones I've found, can anyone provide good one?

For a class `X`:

data class X(val v: String)

If this works

X::v

shouldn't this also work

X?::v

?

how can show list of videos by

kotlin

any one faced this before Plz help me

Is there channel related with exposed for database?

I've an

object

that is quite useful to access statically and dynamically. It has some nested properties and classes, and I am currently serializing it with kotlinx.serialization to save it when the application closes. However for loading, Kotlin does not allow me to assign the object with =, is there a way to assign it anyway or another way to do this? The object again has nested objects inside it, so manually setting each property is a solution I would rather avoid 🙂

what would be the proper way with kotlin coroutines to signal events (like wait / notify in java)?

Not really specific to Kotlin, but to JVM (and indirectly linked :p). Can somebody help? https://stackoverflow.com/q/65486924/11377112

Hi Kotliners, A post xmas question for anyone alive in this time of limbo before the new year! I've got a generics question. I can't understand why there's an error in the following:

interface HexData
object EmptyHexData : HexData
data class Hex(val q: Int, val r: Int, val s: Int)

interface HexDataStorage<T: HexData> {
    fun addHex(hex: Hex)
    fun addHex(hex: Hex, data: T): Boolean
}

class DefaultHexDataStorage<T: HexData> : HexDataStorage<T> {
    private val storage = LinkedHashMap<Hex, T>()

    override fun addHex(hex: Hex) {
        storage[hex] = EmptyHexData // <-- ERROR
    }

    override fun addHex(hex: Hex, data: T): Boolean {
        val previous = storage.put(hex, data)
        return previous != null
    }
}

In the function addHex(hex: Hex), I cannot use "EmptyHexData", and I don't understand why. AFAIU It's a sub-type of HexData, so I thought it would comply with the requirement of being a

T

in this case. What's wrong, and how do I fix it? I tried using a class too, e.g.

class EmptyHexDataClass: HexData

but that didn't work either.