Different java concurrency usage in scala

Different java concurrency usage in scala

class Fetch(val url:String) extends Runnable{
  override def run{
    println(scala.io.Source.fromURL(url).mkString)
  }
}

val urls = List("http://news.com", "http://cnn.com", "http://stackoverflow.com", "http://abc.com")

val threads = urls.map{ url => 
    val thread = new Thread(new Fetch(url))
    thread.start()
    thread
}

while(threads.exists(thread => thread.isAlive)){ }

println("done!")

//////

import java.util.concurrent.Callable
import java.util.concurrent.ExecutorService
import java.util.concurrent.Executors
import java.util.concurrent.Future

class Fetch(url:String) extends Callable[String] {
  override def call:String = {
    scala.io.Source.fromURL(url).mkString
  }
}

val executor = Executors.newFixedThreadPool(5)

val urls = List("http://news.com", "http://cnn.com", "http://stackoverflow.com", "http://abc.com")



val list = urls.map{ 
url => 
val worker = new Fetch(url)
executor.submit(worker)
} 

val allContents = list.map{
    future => future.get
}.mkString

println(allContents)
println(allContents.length)