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How to implement this kotlin ReceiveChannel code properly


How to implement this kotlin ReceiveChannel code properly

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How to implement this kotlin ReceiveChannel code properly
Tag : kotlin , By : Naveen
Date : January 12 2021, 07:00 PM

will be helpful for those in need The reason why it is recommended to declare your function as extension of CoroutineScope is that you need a scope for any coroutine-creating built-in function anyway. You should not be able to call produce without a scope, it should not compile in recent versions of Kotlin coroutines library.
Declaring your function as extension of CoroutineScope is done this way:
fun CoroutineScope.produceNumbers() : ReceiveChannel<Int> = produce {
    for (x in 1..5) {
        println("send $x")
        send(x)
    }
    println("Done")
}
import kotlinx.coroutines.*
import kotlinx.coroutines.flow.*

fun produceNumbers() : Flow<Int> = flow {
    for (x in 1..5) {
        println("emit $x")
        emit(x)
    }
    println("Done")
}

fun main() = runBlocking {
    val flow = produceNumbers()
    flow.collect {
        println(it)
    }
    println("Main done")
}

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Convert RxJava code to Kotlin properly


Tag : java , By : CodeOfficer
Date : March 29 2020, 07:55 AM
Hope this helps In kotlin you can replace interfaces implementations, having just one method, for a lambda expression (doc).
.subscribe(
        { item: Long? ->

        },
        { t: Throwable ->

        },
        {//onComplete

        })
.subscribe(
        { item: Long ->

        },
        { t: Throwable ->

        },
        {//onComplete

        })

Trouble converting Java code to Kotlin to implement an OnChangeListener


Tag : java , By : nabbed
Date : March 29 2020, 07:55 AM
To fix the issue you can do I have this code to implement a listener for a Range Bar library: , Your rangebar is null,
To avoid crash, use like this :
rangebar?.setOnRangeBarChangeListener(object: RangeBar.OnRangeBarChangeListener {
    override fun onRangeChangeListener(rangeBar:RangeBar, leftPinIndex:Int, rightPinIndex:Int, leftPinValue:String, rightPinValue:String) {
        textView.text = "$leftPinIndex"
    }
})
rangebar?.setOnRangeBarChangeListener { rangeBar, leftPinIndex, rightPinIndex, leftPinValue, rightPinValue -> 
    textView.text = "$leftPinIndex" 
}

Annotations not converted properly after changing code from Java to Kotlin


Tag : java , By : kangfoo2
Date : March 29 2020, 07:55 AM
it helps some times Kotlin confuses its own IntRange class with the IntRange annotation of the Android SDK.
Make an import like that giving it another name:
import android.support.annotation.IntRange as AndroidIntRange
fun foo(@AndroidIntRange(from = 0, to = 255) bar: Int) {
}

Implement code after convert Java to Kotlin error


Tag : android , By : user105769
Date : March 29 2020, 07:55 AM
hop of those help? You can use the operators (infix functions) shr and and for the type Int (and Long) in Kotlin.
Just change b with b.toInt():
private fun appendHex(sb: StringBuffer, b: Byte) {
    sb.append(HEX[b.toInt() shr 4 and 0x0f]).append(HEX[b.toInt() and 0x0f])
}

How to implement NIO Socket (client) using Kotlin coroutines in Java Code?


Tag : android , By : Sonal
Date : March 29 2020, 07:55 AM
I hope this helps . As Marko pointed out your code will still end up blocking a thread even when that blocking operation is in the async coroutine. To truly get the asynchronous behavior you desire with Java and Kotlin you need to use the Async version of Socket Channel
With this, you get true asynchronous socket handling. With that class and Kotlin's suspendCoroutine builder method, you can turn the async handlers into suspendable calls.
class TcpSocket(private val socket: AsynchronousSocketChannel) {
    suspend fun read(buffer: ByteBuffer): Int {
        return socket.asyncRead(buffer)
    }

    fun close() {
        socket.close()
    }

    private suspend fun AsynchronousSocketChannel.asyncRead(buffer: ByteBuffer): Int {
        return suspendCoroutine { continuation ->
           this.read(buffer, continuation, ReadCompletionHandler)
        }
    }

    object ReadCompletionHandler : CompletionHandler<Int, Continuation<Int>> {
        override fun completed(result: Int, attachment: Continuation<Int>) {
            attachment.resume(result)
        }

        override fun failed(exc: Throwable, attachment: Continuation<Int>) {
            attachment.resumeWithException(exc)
        }
    }
}
suspend fun AsynchronousSocketChannel.asyncRead(buffer: ByteBuffer): Int {
    return suspendCoroutine { continuation ->
       this.read(buffer, continuation, ReadCompletionHandler)
    }
}

object ReadCompletionHandler : CompletionHandler<Int, Continuation<Int>> {
    override fun completed(result: Int, attachment: Continuation<Int>) {
        attachment.resume(result)
    }

    override fun failed(exc: Throwable, attachment: Continuation<Int>) {
        attachment.resumeWithException(exc)
    }
}
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