import javax.sound.sampled.AudioInputStream

fun test(ais: AudioInputStream) {
    ais.readNBytes(ais.available()) // compiles fine
}

import <http://java.io|java.io>.ByteArrayInputStream
import <http://java.io|java.io>.ByteArrayOutputStream
import javax.sound.sampled.*
import kotlin.concurrent.thread

fun main() {
    val format = AudioFormat(
        192000f,
        16,
        1,
        true,
        true
    )
    val info = <http://DataLine.Info|DataLine.Info>(TargetDataLine::class.java, format)
    if (!AudioSystem.isLineSupported(info)) {
        error("Line not supported")
    }
    val line = AudioSystem.getLine(info) as TargetDataLine
    line.open(format)
    line.start()
    println("Start capturing...")

    val ais = AudioInputStream(line)
    val baos = ByteArrayOutputStream()
    var stop = false
    thread {
        Thread.sleep(3000)
        stop = true
    }
    while (!stop) {
        val buffer = ais.readNBytes(ais.available())
        //workaround: 
        //val buffer = ByteArray(ais.available())
        //ais.read(buffer)
        baos.write(buffer)
    }
    line.stop()
    line.close()
    println("done")
    val recorded = AudioInputStream(ByteArrayInputStream(baos.toByteArray()), format, baos.size().toLong())


    readLine()

    val clip = AudioSystem.getClip()
    clip.open(recorded)
    clip.start()
}

plugins {
    kotlin("jvm") version "1.3.61"
}

group = "lastexceed"
version = "1.0-SNAPSHOT"

repositories {
    mavenCentral()
}

dependencies {
    implementation(kotlin("stdlib-jdk8"))
    compile(files("src/main/resources/jnativehook-2.1.0.jar"))
}

tasks {
    compileKotlin {
        kotlinOptions.jvmTarget = "1.8"
    }
    compileTestKotlin {
        kotlinOptions.jvmTarget = "1.8"
    }
}

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.idea

Usage of API documented as @since 11+