Simple Minecraft 1.9 Launcher

MinecraftLauncher.kt

import java.io.File
import java.io.FileOutputStream
import java.io.IOException
import java.nio.file.Files
import java.nio.file.Path
import java.nio.file.Paths
import java.util.*
import java.util.zip.ZipEntry
import java.util.zip.ZipFile

class MinecraftLauncher {
    fun main(args : Array<String>) {
        Launcher.launch()
    }
}

class Launcher {
    companion object {
        fun launch() {
            var javaParameters = "-Xmx2G"
            var gameDir = "\"D:\\Games\\Minecraft\""
            var version = "1.9.2"
            var nativesPath = "$gameDir\\versions\\$version\\natives"
            var librariesPath = "$gameDir\\libraries"
            var libraries = arrayOf("$librariesPath\\oshi-project\\oshi-core\\1.1\\oshi-core-1.1.jar",
                    "$librariesPath\\net\\java\\dev\\jna\\jna\\3.4.0\\jna-3.4.0.jar",
                    "$librariesPath\\net\\java\\dev\\jna\\platform\\3.4.0\\platform-3.4.0.jar",
                    "$librariesPath\\com\\ibm\\icu\\icu4j-core-mojang\\51.2\\icu4j-core-mojang-51.2.jar",
                    "$librariesPath\\net\\sf\\jopt-simple\\jopt-simple\\4.6\\jopt-simple-4.6.jar",
                    "$librariesPath\\com\\paulscode\\codecjorbis\\20101023\\codecjorbis-20101023.jar",
                    "$librariesPath\\com\\paulscode\\codecwav\\20101023\\codecwav-20101023.jar",
                    "$librariesPath\\com\\paulscode\\libraryjavasound\\20101123\\libraryjavasound-20101123.jar",
                    "$librariesPath\\com\\paulscode\\librarylwjglopenal\\20100824\\librarylwjglopenal-20100824.jar",
                    "$librariesPath\\com\\paulscode\\soundsystem\\20120107\\soundsystem-20120107.jar",
                    "$librariesPath\\io\\netty\\netty-all\\4.0.23.Final\\netty-all-4.0.23.Final.jar",
                    "$librariesPath\\com\\google\\guava\\guava\\17.0\\guava-17.0.jar",
                    "$librariesPath\\org\\apache\\commons\\commons-lang3\\3.3.2\\commons-lang3-3.3.2.jar",
                    "$librariesPath\\commons-io\\commons-io\\2.4\\commons-io-2.4.jar",
                    "$librariesPath\\commons-codec\\commons-codec\\1.9\\commons-codec-1.9.jar",
                    "$librariesPath\\net\\java\\jinput\\jinput\\2.0.5\\jinput-2.0.5.jar",
                    "$librariesPath\\net\\java\\jutils\\jutils\\1.0.0\\jutils-1.0.0.jar",
                    "$librariesPath\\com\\google\\code\\gson\\gson\\2.2.4\\gson-2.2.4.jar",
                    "$librariesPath\\com\\mojang\\authlib\\1.5.22\\authlib-1.5.22.jar",
                    "$librariesPath\\com\\mojang\\realms\\1.8.18\\realms-1.8.18.jar",
                    "$librariesPath\\org\\apache\\commons\\commons-compress\\1.8.1\\commons-compress-1.8.1.jar",
                    "$librariesPath\\org\\apache\\httpcomponents\\httpclient\\4.3.3\\httpclient-4.3.3.jar",
                    "$librariesPath\\commons-logging\\commons-logging\\1.1.3\\commons-logging-1.1.3.jar",
                    "$librariesPath\\org\\apache\\httpcomponents\\httpcore\\4.3.2\\httpcore-4.3.2.jar",
                    "$librariesPath\\org\\apache\\logging\\log4j\\log4j-api\\2.0-beta9\\log4j-api-2.0-beta9.jar",
                    "$librariesPath\\org\\apache\\logging\\log4j\\log4j-core\\2.0-beta9\\log4j-core-2.0-beta9.jar",
                    "$librariesPath\\org\\lwjgl\\lwjgl\\lwjgl\\2.9.4-nightly-20150209\\lwjgl-2.9.4-nightly-20150209.jar",
                    "$librariesPath\\org\\lwjgl\\lwjgl\\lwjgl_util\\2.9.4-nightly-20150209\\lwjgl_util-2.9.4-nightly-20150209.jar",
                    "$gameDir\\versions\\1.9.2\\1.9.2.jar")
            var mainClass = "net.minecraft.client.main.Main"
            var username = "QuadX"
            var assetDir = "$gameDir\\assets"
            var assetIndex = "1.9"
            var uuid = UUID.randomUUID().toString().replace("-", "")
            var accessToken = "1a2b3c4d5e6f7g8h9i0g"
            var userType = "mojang"
            var versionType = "release"
            var fullscreen = false
            var connectToServer = false
            var server = mapOf(
                    "ip" to "127.0.0.1",
                    "port" to "25565"
            )

            var run = "java $javaParameters " +
                    "-Djava.library.path=$nativesPath " +
                    "-cp ${libraries.joinToString(";")} $mainClass " +
                    "--username $username " +
                    "--version $version " +
                    "--gameDir $gameDir " +
                    "--assetsDir $assetDir " +
                    "--assetIndex $assetIndex " +
                    "--uuid $uuid " +
                    "--accessToken $accessToken " +
                    "--userType $userType " +
                    "--versionType $versionType" +
                    "${if (fullscreen) " --fullscreen" else ""} " +
                    "${if (connectToServer) " --server ${server["ip"]} --port ${server["port"]}" else ""}"

            var _nativesPath = Paths.get(nativesPath.replace("\"", ""))
            if (Files.notExists(_nativesPath)) {
                Files.createDirectories(_nativesPath)
            }
            if (Utils.isDirEmpty(_nativesPath)) {
                var nativesPaths = arrayOf(
                        "${librariesPath.replace("\"", "")}\\org\\lwjgl\\lwjgl\\lwjgl-platform\\2.9.4-nightly-20150209\\lwjgl-platform-2.9.4-nightly-20150209-natives-windows.jar",
                        "${librariesPath.replace("\"", "")}\\net\\java\\jinput\\jinput-platform\\2.0.5\\jinput-platform-2.0.5-natives-windows.jar"
                )
                for (path in nativesPaths) {
                    Utils.unzip(path, _nativesPath.toString(), arrayOf("META-INF"))
                }
            }

            var p = Runtime.getRuntime().exec(run)
        }
    }
}

class Utils {
    companion object {
        fun unzip(zipPath: String, unzipPath: String, skip: Array<String>) {
            try {
                var zipFile = ZipFile(zipPath)
                var enu = zipFile.entries()
                while (enu.hasMoreElements()) {
                    var zipEntry: ZipEntry = enu.nextElement()

                    var name = zipEntry.name
                    if (skip.find { it -> name.contains(it) } != null) continue

                    var file = File("$unzipPath\\$name")
                    
                    var parent = file.parentFile
                    if (parent != null) {
                        parent.mkdirs()
                    }

                    var inputStream = zipFile.getInputStream(zipEntry)
                    var fos = FileOutputStream(file)
                    var bytes = ByteArray(1024)
                    var length = inputStream.read(bytes)
                    while (length >= 0) {
                        fos.write(bytes, 0, length)
                        length = inputStream.read(bytes)
                    }
                    inputStream.close()
                    fos.close()
                }
                zipFile.close()
            } catch (e: IOException) {
                e.printStackTrace()
            }
        }

        fun isDirEmpty(directory: Path): Boolean {
            var dirStream = Files.newDirectoryStream(directory)
            return !dirStream.iterator().hasNext();
        }

    }

}

Only for Windows

how do we run this?
i dont understand